I have done them many times without touching the pan. A few tips (as if you didn't know) would be to be careful not to gouge the metal around the seal on removal. I use a small screw driver, hammer and I lay something across the crank if I wanna pry. Clean the area out good with a small screw driver and some brake clean. Then I grease the seal inside and the edge of the crank, I also ALWAYS apply a light coat of Permatex non hardening sealer to the outside of every seal. It makes it go in easier and seals imperfections in the seal to cap. Tap it in with a large socket till its flush. Don't forget some pipe sealant on the flywheel bolt threads.