Can the remote front panel cable be extended beyond the stated 100 foot length?

Can the remote front panel cable be extended beyond the stated 100 foot length?

The cable carries RS232, +5V power, and two special purpose lines.  The +5 V power is the limiting factor in cable length, and the factor that drives the need for 26 gauge wire  and a cable shield (if there's no other common ground). 

However, we have had customers who were able to extend the length by doing the following:

1. Do not wire pins 1, 8 and 4 on the remote cable
2. Provide external power of 5 volts to pins 1 and 8 on the Remote Front Panel.
3. Tie pin 4 on the WVR7100 to +5 through a 1K resistor.

For extreme lengths, a RS232 repeater/amplifier might be employed.