The leater on the door of my pacemaker 4x5 has always had lot of bumps in it. I imagine they correspond to where screws are, but I have never figured out how I can get rid of them, short of recovering the camera. I imagine that a mild saddlesoap product would be good to keep the leather conditioned on the camera, and that the bumps may lessen or go away. Any ideas?

While I"m not an authority on the subject, It's my belief that the bumps are caused by corrosion between the brass rivets and the aluminum bed. Moisture usually brings it on and the oxidization starts taking place along with some Galvanic action between the two metals.

It's not that different than the rusty spots under the paint on your car.

Without stripping and cleaning the spots and then re-covering, they won't go away. Taking care of the leather and keeping the camera in a dry, well ventilated place will help from accelerating the problem.

Once the rail guide(s), rails(yoke) and blocks are removed from the bed assembly the edge of the leather is accessible and can be removed by carefully pulling it from the bed. The most critical part to remove is the chrome strip along the front edge, it is a press fit-easy to bend or deform.
Once the corrision is removed, a good quality contact cement should be used to reattach the leather.
Charles