I have a stick built alumisacpe 26' so it isn't quite the same thing as we are discussing here but I have a stabilizer problem I have been working on for a while and thought I would chip in what I have found out.
I have BAL scissor jacks in the back and electric landing gear in front. I use scissor type chocks between the 2 axles. All together they do a great job of holding the trailer in place and upright without the truck attached but do very little for stability side to side. It doesn't rock side to side but it slides side to side a lot.
The front pole jacks have a bit of slack in the telescoping mechanism and I don't think they are that stiff in the way they mount to the front of the trailer so they have a limited effect on lateral motion.
The rear scissor jacks do almost nothing to stop lateral motion. You might think the tires
and suspension would hold the trailer in place side to side and they do but there is enough spring in it all to let the trailer sway quite a bit.
It's not like there is no control but if someone is walking around the trailer moves enough to wake up anyone who is sleeping.
To counter this I have tried putting a come-along between the front jacks to put them in a bind and remove the slack. I put it on an angle so that it provided a little triangulation too. That helped about 50% which seem logical since it may take out the front sway but would do nothing for the rear.
Being a cheapskate from way back, I've tried to come up with a solution that would cost little or nothing while still being convenient.
Since come-alongs are pretty cheap I considered using 2 at the front and 2 at the rear in an X arrangement to triangulate the setup. I think it would work but the thought of crawling under the trailer to install them every time we setup or take down didn't appeal to me.
I also thought about making brackets to mount brace pipes that could swing up and stow with clips when not in use and swing down to attach to the scissor jacks to stabilize things. Again that would require crawling around under the trailer which isn't appealing.
The ground clearance under the rear of my trailer is about 26 inches. Many support solutions that would work just fine on a fiberglass RV will not reach on mine.
The key to stability is triangulation. You need some kind of diagonal bracing to keep things steady. I like the stabilizing jacks: https://www.amazon.com/BAL-R-V-Produ...al+stabilizers
If my 5er didn't already have scissor jacks I'd probably buy this but the price is more than I want to spend. As is everything else.
I like these lock-arm stabilizers:
Again they cost too much since I would need at least 2 sets but more importantly I don't like the way the bolt clamps the two tubes together. It seems to me that the inner tube will wind up with lots of dents in it from over tightening, the bolt will strip out it's nut from repeated use and the bolt may fall
out if it isn't tightened again in the retracted position. The videos and instructions don't mention tightening the bolt in the up position. There is also a real possibility of forgetting to undo the bolt before raising or lowering the jacks.
I really like steadyfast stabilizers: https://www.amazon.com/Stabilizer-Sy...lock+arm&psc=1
I really don't like the price though.
I think I could make up something like the steadyfast stabilizers myself for a lot less using a piece of pipe, a heim joint, a piece of angle iron, some hardware and a wing nut I make myself from misc. junk I keep.
As far as clearance goes it's all a matter of where you mount the stabilizer. You will get more stabilizing action by having stabilizers as far to the outside of the RV as possible but it doesn't have to be at the very back.
What really counts as far as ground clearance is concerned is escape
angle. That is the line between the tire contact patch on the ground and the lowest part of the rear of the trailer. If the stabilizer is above this line then it will be less likely to be the first thing to drag on the ground.
By moving the stabilizers forward a bit they can be ahead of this line and clearance will not be an issue.
Ground clearance in the front hardly matters unless you really get into wilderness off road camping.