This is going to raise a lot of hell but I am planning to bed stringers with 5200, before glassing. This is where I got the idea. I don't have a name but the poster seems experienced, he's all over this other forum.
100 ways to skin a cat... I used polyester on my build because that is what I knew, tore long strips of matt and wetted out two layers and sat the stringers on it, if you frey the strips on both sides you wont get a hard line of glass. Put a little weight on top, don't go crazy with the weight and push all the resin out. Floors and stringers were ruffed up with 24 or 36 grit to make sure we had a good mechanical bond as well.