Just buy the damn spring compressor retard. Hell, I have seen guys work on cars all day with just jacks holding the car up. I also know guys that swap motors solo. Sure it might be okay but if you make it a habit of working on cars that way, you will eventually hurt yourself. My uncle used to work on his work truck with just a 5 ton jack holding it and one summer he was replacing a tranny and the jack went and nearly killed him. Luckily he was paying attention and rolled off the creeper and only suffered a broken rib. Had it been a car, it most likely would have killed him but since it was a ford dually it was high enough for him to fit between the ground and the bottom of the truck. Now he uses jack stands everytime (or my aunt will kick his ass).