While cross band repeat is good to have in reality I've only used it twice when I ran the finish on Concord Pond.
Communications from the start to finish has always been erratic there so I used to place a car with a Yaesu FT-8800R under the power lines about a mile from the finish and then link with an HT.
Later we found that it was easier to just erect a mast with a yagi pointed to the start.
FYI - crossband repeat is where you have a better situated radio receive on 440 while simultaneously transmitiing on 2 meters. You transmit to it on 440. When receiving the better situated radio retransmits the 2 meter signal on 440 for you to receive.
Field programming? At every event I have several people come to me to program their (Yaesu) radios.
Frequencies and PL tones for repeaters - that's pretty much what I need to do for them.
Thank you for volunteering.