Hmm.. ok I've looked at a bunch of KVMs, but nothing mentions using them backwards.
I've now thought I have a second option that might actually be better (maybe). My simpit is designed with a keyboard drawer and the mouse just sits on the right console, so I can easily use a wireless keyboard/mouse combo if I put the reciever somewhere between the desk and simpit. Then I can just take the keyboard/mouse to the desk or the simpit, depending on what I'm doing.
I also found a PC video splitter on COMPUSA that is supposed to be very high bandwith (200Hz) and up to about 1900x1700x32 video resolution and able to run 2 analog monitors at the same time. With that, I should be able to run a monitor in the simpit and another on the desk. Might even be cool for people watching, as they can look at the desk monitor rather than over my shoulder.
Providing I can find all the extension cables I need for the audio, USB and video, I can keep the CPU on the desk, rather than in the simpit.