The factory installed stabilizer jacks are simply in the wrong locations. I had four of the aluminum stack jacks that I kept from my last trailer and with some experimenting I found that if I put them about 6' in front and in back of the axles I didn't even need the factory ones which I removed and don't even have them on my trailer anymore. Now if you have a long trailer say 30' and have a major living area at the rear you might need something at that end, but all I have is a bedroom that is only used to sleep in so there is almost no walking around in the last 8' or so of my trailer.
I had used these jacks on my previous 26' TT for over 25 years for a rock solid setup so I just felt their use had to help the poor stabilization with what came on our new trailer. As far as the forward/back movement I've never had that since I make sure my little cheapo wheel chocks and well planted against both sides of the wheels on both sides of the trailer (4 chocks total).
IMHO the secret to stabilizing a trailer is the proper support locations and getting a good pressure on the jacks ... not lifting the trailer, but doing a similar procedure that even things like the Strong Arm site recommends with their product. I found the only way to do this was to use the tongue jack.
Larry