Up:
"2-100 Amp 120/240V, single phase disconnects, which serve 2 permanent office trailers, which have to be powered back up. So single phase secondary is a must now."
IMHO, there should be no effect on the trailers, as long as there is no 240 volt specific equipment within them.
Most (not all) HVAC that I have come upon is happy with 208 to 240 volts.
Either way...75 KVA would be my way to go.
