I would suggest using Dow749 (McMaster.com). Be sure to allow room for the Lexan to expand in heat and not blow apart the wood frame. About 1/8" all around for 2 ft square panel. M Then start by masking off the area on the Lexan where you don't want the bedding. Lightly scuff the Lexan surface with 280 - 300 grit paper that is to be bedded and clean with alcohol. Mask off the areas on frame and Lexan (inside and out) at edge of bedding seam. Make sure all areas you don't want bedding are masked. Apply liberal amount of 795 and press Lexan into it. Use plenty so you have no air pockets. Quickly tool off excess using plastic spreader before it skins over and carefully pull the masking tape. Follow up the next day by lightly hitting the bedding with a scotchbrite pad - this will flatten out the gloss on the silicone. This silicone is used for glass panels
on high-rise buildings and many boat
hatches on the market. Caution... It is very black! Keep it off older gelcoat!