Seasonal Caulk
I have just finished installing boots in my RV9A and haven't flown the plane yet to tell how well they work. Prior to installing the boots, I needed something to tide me over for a trip I took about a month ago. I got into the cockpit with a caulking gun and a tube of one of my favorite products, "Seasonal Caulk" and sealed all the openings in the floor pans and such. I sealed around the seat belt anchors, around the spar panel and a number of small openings. It really helped. A few weeks later, when I started the job of installing the boots, all the caulk strips came off like unzipping a zipper. I really like that suff for things like airplanes that have to come apart every so often.
Good Luck