[Festus2]

This question about jack placement was just asked on the forum today (Questions on a Cougar 5ver) in another thread so you might want to check that post. You can use a jack and place it on the spring mounts as you suggested ( not on the axle!!) or you can drive up on a raised ramp with one rear tire leaving the one you want to service raised in the air. Just make sure the wheel on the ramp is chocked. The ramp can be made so that it has a "hollow" or low spot where the tire sits so that it doesn't roll back or forward.

I am not sure whether hitching the trailer and using the stabilizers is necessary so long as the trailer is stable and secure. You certainly do not want the trailer to move while you are working on it.