Hi,
The good news is that in the area you live there should be tons of jobs. You know that LPNs are utilized most often in LTC and doctors offices here, right? A clinic, Docs office or school nursing if you can get it will probably be the easiest on your back and also offer the days you want. Have you heard anything about AACC working with AAMC to hire LPNs? I wasn't sure if that was just a rumor or not but again I think AAMC often requires rotating shifts.
As for the risk for injuries, imo, sadly it kind of goes with the job. There are "no lift" facilities and the principles of good body mechanics but imo the truth is that very often we are at risk no matter how careful we are. Just my two cents and I'm sure others will write in and hopefully I am wrong about this one.