I uee the Rob Max method of using a hand scraper ground to a rounded surface. Just a cheap Red Devel paint scraper. Grind the blade to an arc. You can scrape all your glue away and level the uneveness with it.

Then I switch to hand sanding with a 40 grit sanding belt that I wrap wround a soup can. My entire inside finishing takes me about two hours of sweat. I glass right on the 40 grit rough surface. You want to talk about adhesion!

The only other thing I do is sand with the strips in the cockpit area where it will be in open view.