I have done many a boat with this stuff. I have used a propaine hand held gun with a flat tip to make the flame wide.....I found after getting the hang of it, using a small hand held torch used for roofing works faster, but you have to know what your doing, or you will make swiss cheese out of it in a hurry.
I use 1x2 ir 1x3 strapping and make a frame from bow to stern in a large arc. support it with uprights every 4 or 5 feet. use rags where the wood hits the boat, and over any sharp pieces that will tare the wrap. You can use duct tape to hold the rags in various locations. Then I use twine to "tie" the wood frame down to the sides of the boat.
I live in Canada, so we build them for snow load too. You might not have to worry about snow where your at, so you might be able to get away with a lighter design.
As for using a heat gun, if you mean the small electric hand held type, you might want somthing a bit quicker....it'd take you all day.
Also, make sure you cut a large enough piece that it hangs down to the ground all the way around the boat. You can use twine or rope to wrap aound the base, then flip the swrink up over the rope and stick it to it's self. Cut little slits so you can tie another piece of twine around that rope you just incased in the wrap and tie it down to your trailer. This will keep it from blowing off if you cruise down the road.
Hope that made sense....
Yeah makes sense to me..... ask if you need more info. forgot to mention a few things.... i use wood screws to hold all the wood together, for the arc I overlap the wood 8" or so and screw it together. The frame will take 1/2 a day to build, and it will take you the other 1/2 to finish up with the wrap. Set aside a good amount of time and don't rush it.
Not sure on how big of a boat your talking about.... if it's a big one, we have used scissor lifts to get up to the top. You want to make sure you can get to every part to get tight. You can also get little doors with a zipper for access. You would be surprised how many time you have to get back in to get something out!!!
Also if your stroring it for a long time outside, make sure you cover all the outside of the boat (not just 1/2 down the gel on the outside) or the sun will fade the gel only where it hits it, and it will look stupid next year. Kinda like a farmer tan