How much pressure/torque on "stabilization" jacks?

It is an RV. The 'V' stands for Vehicle. Vehicles are on wheels which are mounted to springs. Springs have a tendancy to, well, spring. It is not a house. Stabilizers do just that. They stabilise, somewhat. There will always be some jiggle & shake. Get used to it.

Put blocks under the stabizers & snug them up. If on dirt snug them up again after they have settled the next day.

At least it is not like a boat at anchor where there is always movement & there is not a thing that can be done about it.