Thanks for those suggestions. I already have a solution for USB that seems to work OK: A "Tripp" brand USB cord with ahub with a signal -- what? -- repeater? amplifier? I think I have a couple of the twenty-five footers, and they work in tandem as extensions to a USB-to-miniUSB needed to connect to the body.
I was wondering if I find a WiFi unit at a reasonable cost if my tethering can work over Ethernet (cat5e cable). There would be other problems WiFi would solve, like impossible cable situations. "docHoliday" here has described some uses of WiFi, no cables, for staff to watch the images coming across in an adjacent room. Clients love this stuff!