The Texas version looks pretty functional and reasonably priced. Not the greatest marketing copy, though.
There was a guy several years ago who was selling spikes to add to DriDeck mats for this same purpose. Don't believe he's still in business, but I still use mine. It stays on the deck, is compact and drapes the fly line.
You could probably make your own with plastic tubing and nylon bolts like they use for license plates. I'll take a photo of my mat tomorrow and add to this post.