Zippy's answer is a great one for the space-confined.
Bolt your equipment to a piece of wood, and C-clamp the wood to your working surface when you want to reload.
When you get a house, if you don't have enough room for your dream-bench, do this:
Build a bech that you can use for multiple purposes (repair, woodworking, reloading, whatever)
Build a strong flat-topped bench, and mount a woodworking vise to it:
Then, for all the other things you want to do with your bench, use the wood vise as the basis for other things. Bolt a shop vise to some wood, and hold the whole deal in place with the wood vise:
Do the same thing with your reloading press(es).
You can also clamp handheld tools, such as a belt sander (upside down) and use this setup as a table sander. A foot pedal operated switch, can be set up for turning the power on/off.
Very versatile, if you're hard up for space.