I've made 1/2 width fishing Tramps out of shadecloth and 1" strapping. Very strong, using carbon fiber wind surfer masts as the long bars and PVC pipe as the spreaders. I plan on making full width Tramps for my TI, but it's not a top-of-the-list project, so may be a while.
I wouldn't use too open a material like netting, or it won't stop any water splashing up, but I also want material that breaths (lets the air through fast) so as not to act as another sail when coming off a wave.
The first few week the Hobie tramps were available, a few people flipped their AI's using them. I have a set, but only use them in calm conditions. I've cut one side in half already to make 1/2 tramps which I think are much safer in rougher conditions.
My Sprayskirt is to keep most of the waves from getting into the cockpit and keeping much dryer. It helps a little on the nose diving, but that's just a bonus.http://www.kayakingbob.com/sprayskirthttp://www.kayakingbob.com/sprayskirt-purchase
- - - - - - - - - - - - - - - - - - - - - - - - - - - 2007, 2009 & 2010 Hobie AIs and a 2010 TI