EIA485 or LVDS is simple. Voltage drop is expected, or you're paying too much for cable. You can budget for something crazy like 90 % signal loss! As long as there's about 50 - 100 mV at the remote end itll work.
If you're worried about the distance, just get a big drum of the said cable and try it, I think you'll be suprised. If the command data rate is low (very likely), you don't need fancy low loss cable, you could probably use doorbell wire and it work just as well. After all telephone cabling is something like 22 AWG and can carry mental ADSL data rates OK.