The underside of the lip is really not that tough to sand smooth and flood with epoxy. I just used some 80 grit sanding belt material and with my fingers just sanded the underside. With no exaggeration, this was probably 15 minutes. then with the boat upside down, I just flooded the underside surface with epoxy. You have to prop the boat a bit and try to get the lip level as you can. But the short story here is; I found it fairly easy to smooth out.

I clamp on my first layer of lip material fairly tight and it's epoxied on solid. Then I build up the layers doing one each day. I don't do the whole group of layers at once because I like to overlap the joints totally smooth.

Question: with your method, did the lip fit well and did you just prop it up to height on the coaming to epoxy it? In other words, was it tight enough to stay up in position so you could wipe up any epoxy under it?