What size flies are you throwing at those bones?
One thing to noticed about the BTT is it doesn't really throw razor tight loops. Also, it's heavier than the Grand Slam, (i.e... for an 8wt, it's 245g for a BTT vs 235g for the GS (both of which are more of the weight of a standard 9wt line) vs 210g (normal 8wt in normal conditions)). So trying to punch it in the winds with a very heavy line to look at distance shots can, in-effect, cause the rod to be over powered or even collapse on the shoot, especially dragging along a big heavy fly. WHat you are really doing with those lines is trying to convert an 8wt rod into a 9wt rod, but the 8wt rod doesn't have the backbone to handle punching that heavier line into the winds. Ok if you have a stiff 8wt and just using those lines to general purpose fishing at normal distances in normal conditions, but not so much if things, distances and conditions changes. And with rods that are not so stiff, if you sneeze wrong, you can overpower the whole thing and you'll wonder why your casting is starting to fall apart.
Also, there is a fine line between over powering and getting the right line speed to still be effective and keep the loop together. The Titan is 280grains in the 8wt (more like a 10wt line). Nothing presentation for a Titan, but chucking heavy or bigger flies in strong winds can work, tho not that great for distances and crashes on the water. Even tho you'll see wave action to mask the disturbance of a heavy crashing line, it's not a line that I would pick for big bones. They got big for a reason.
In high winds, where the BTT will not do as well is the weight is further back in the head. On the shoot, as soon as it's starts to roll over the taper, the loop will start to open up and the winds will work to bash the loop down. You may get most of the line rolled out heading straight into the wind, but you may not get the leader to unroll out. When casting it on the lawn, practicing casting into the wind, cast it, lay the rod out and walk out and look at the results. Same with the Grand Slam line.
With the Grand Slam line, the main part of the weight in the head is about 3-10ft from the end of the line. So the thinner part of the head will be pulling that along and you'll notice that the top leg of the loop will lay down closer to the main running line of the loop. That will help tighten up the loop and penetrate more into the wind. Then the last roll over, tho not being graceful, will throw all that energy in one shot into the leader and sling it out there in front of the line (and whatever is tied onto it). Whereas the Triangle Taper of the BTT will disperse the energy over a longer distance, tho constantly going down in diameter throughout the taper, might run out of gas when it hits the leader, in a head-on high wind scenario. I might get a lot of boos and hisses for making that comment, but try it out in a head-on high wind condition and you'll see what I mean.
I remember the Wind Master as Tailer mentioned. Like Steve mentioned, the Titan is the next gen of Windmaster lines. However, it was lighter that the Titan, with a much longer head. Good to carry more line in the air, but a fine balance between a little heavy on the weight and too much weight. Again, you are trying to force an 8wt into what it doesn't want to do. As Tailer also mentioned, you'd be better off using a 9wt bonefish line (long and thin to cut the wind) on a 9wt rod and will allow you to throw those slightly larger bonefish flies for those big bones without blowing up the water when it lands. It will also help you to achieve some good distances.
With that setup, casting in the wind, practice throwing your back cast up higher (going back and stretching it out with the winds) and your front cast down lower, going into the winds. Reduce the number of false cast you make. I'd be slow water hauling, then one false cast or so to straighten things up, then shoot it. Be more involve with tip casting to help tighten that loop up. That will dramatically help to cut the wind.
With all that being said, you might say... Why "razor tight? Think of a bullet shape piercing the wind when casting straight into it. But in the opposite direction with your back cast, where you are now casting "with" the wind, you want to open up your loop and allow the wind to drag it back further like a kite. So a cast into the wind scenario is tight tip style casting going low and straight into the wind and the back cast is shooting up higher with more of a open style of loop cast (purposely opening up your back cast loop) with longer delays to all that loop, to fully straighten up behind you before you start your movement going forward. The opposite is true casting "with" the wind. Whereas low tight loops on your back cast and high wide open lofty loops on your front casts and shoots, going "with" the winds.
So do this experiment.... Try taking your 9wt rod out somewhere to cast and grab both the 8wt BTT and the 8wt Grand Slam lines to try. Now with that 9wt rod, really aerialize the whole head out of each of those lines (again, they are both the weight of a standard 9wt line) through the tip top guide and then really punch it out with a tight loop and using all your distance casting skills to do so. Remember, you are merely throwing bonefish flies that are scaled up a bit to catch those big bones attention, not throwing big heavy redfish or striper flies. Then see how that works for you or not. I'd be interested in hearing the results of that experiment.
Interestingly enough, if you can get perpendicular to the wind to your target, where the winds are coming from your left side (be it you are casting right handed), you could throw a 6wt in 25mph winds, all day long. And if the winds are on your right shoulder, then just simply back cast to your target. But nevertheless, my advise is to bring both the 8wt and the 9wt. If you luck up and get calm conditions, then break out the 8 and if the winds are howling, grab the 9!
I hope I didn't loose anyone with this explanation.
Good luck.
Ted Haas