Raising 5th Wheel When Landing Gear Malfunctions

What is broken?

If it's the motor, you may be able to hand crank.

Otherwise, the bottle jack idea should work but be careful to make sure the wheels are well blocked.

You may also need some wood blocks for the bottle jacks to raise it high enough.

Again, be careful as you could easily knock the trailer off the jacks when hooking up.

Personally, if I had the time and there is someone reasonable available, just get it fixed.