If you have hydraulic landing gear, it's pretty iffy. The hydraulic pump pulls quite a few amps (at least 50 amps at 12V). The truck-to-trailer connections probably won't pass enough power. But you probably won't hurt anything trying except possibly blow a fuse in the truck.
If you have jumper cables, get another car or truck to supply power directly to your trailer battery cables. Be sure to get the polarity right.