The jacks I was referring to are the BAL light trailer stabilizing jacks.
They can be installed or replaced in less than 5 minutes with 3 self-tapping screws. They only stick down about 2 1/2 inches below the frame when retracted. I've never had a customer rip one off even on very low pop-up trailers. The only ones I've ever replaced where damaged when the owner tried to drive away with the jacks still down...opps. The screw mechanism is very simple and reliable. I cut the curved portion from an extra handle and use it in an 18 volt cordless drill to raise and lower them. Works great.
My only negative comment is they don't come with the 6 inch round feet (not shown in pic above). You have to order them separately but their definitely worth having.