Just wanted to close this out in the hopes that another n00b might someday benefit from this thread...
I ended up going with Camco EAZ Lift Scissor jacks, which seem sturdy, smooth and well made. I actually took a different turn from my usual MO (just ask my wife) and read the directions that were included - this lead me to mount the jacks in front of the aforementioned standoffs - putting them on the standoffs would have created a situation where the jacks could have been damaged/sheared off in a driveway or something,because they would have been the (new) lowest point.
Right was easy, left took some finagling as the sewage drain was very close, but it fit well. The screws on the left do look a little "jacked up" (and they are), but it is solid.
The install took about an hour. I consider myself moderately mechanical. The hardest part was rolling my aching 43 year old back around in the gravel.