I checked the listing of custom functions, and, at least, with the ones that can be set via the camera, there isn't a way to change the behavior of the pad. It's possible that there is a way, using a PC or older Mac with the special cables (MC-33 and MC-34), to reset everything, but hardly anyone has the Photo Secretary software, nor the cables.
As long as you can get the center focus point lit up, you might be ok, if you're only using MF lenses. At that point, I would try to score an A screen or either the L or J screen. The A and L screens have split-image rangefinder circles, and the J screen has the microprism spot in the middle. Of the three, the J screen seems most common on evilBay.
The Cs mode isn't really silent. It makes an F5 sound like an F3 with a MD-4 that's running on weak batteries. You definitely hear the shutter and the mirror box in action. In my experience, even the Single Shot mode is reasonably quiet. Just test fired mine, and it's no louder than an F2 or an F3.
With respect to the prices, if you can, try to barter with them on it. If you can get it for close to what they paid for the camera, it may be a good deal. If they're fairly firm, I'd walk away and plan to head to Seattle. One of the bodies is pretty decent, some minor paint wear, etc, but no peeling of the rubber surfaces. The other one is pretty worn. They both were former rental cameras. The fairly decent body has a serial number in the 306xxxx range, and the worn one is the 2263rd F5 built by Nikon (first one was 3000001). Very early. My current one is in the 3056xxx range, serial-wise.
The F5 didn't go through many changes over its production, unlike the F4, where it'd be best to get a higher serial number body for all the improvements (249xxxx or higher). Supposedly early bodies tended to eat batteries for lunch, but I had the 4005th body made, and it still was running @ full power 2-3 months after I'd installed a set of eight Energizer lithiums.
Anyway, wish you luck with things. If you do decide to come down, send me a PM and I'll see about getting a few other APUGgers together for a gathering.