Oh dear, we would hate for you to give your bottom away!

Some clever people we know purchase cardboard cake rounds in the same size as their springform pans. They wrap them completely and smoothly in foil, folding any extra foil to the bottom side of the cake round. Then they clamp the cake round in the springform pan rather than the metal bottom that came with the pan, assemble and bake their cheesecake, and present the cheesecake on the cake round, not caring whether or not they ever see it again.

You may need to use a light hand packing in the cheesecake crust, but it is surprising how much stability the cake round has when supported all around by the springform rim. If you're worried, you can use two cake rounds covered in foil and still probably fit them in the groove of the springform pan.

We would definitely put a rimmed baking sheet on a separate rack under the cheesecake in the oven to catch drips, since the foil-wrapped cake round might not form quite as good a seal as the springform pan bottom. (Actually, we use the baking-sheet insurance whenever we bake a cheesecake, since a bit of butter from the crust always seems to drip out, and it smokes if it hits the bottom of the oven.)

If you have indeed lost your bottom, you can always fall back on the foil-wrapped cake round solution as long as you need to.