Your wall-wart charger will not harm your batteries - period. It's just too weak to do any damage. I have flying buddies that put their batteries on charge when they get home from the field and leave them on charge until they go fly the next time whether that's the next day or the next month. It's never done any harm. Do I recommend this? NO! But it simply doesn't hurt either. You can rig a timer so you can charge for 8-10 hrs when you get home and then 1 hr every day until you fly next time and NEVER worry about having charged batteries. Cycle them? Sure, doesn't hurt to do that. Might even be a good idea. Don't know for sure as I haven't done it in 30+ years of flying and never had a problem.

DEFINITELY GET AN ESV AND MONITOR YOUR BATTERIES AT THE FIELD. This is the best advise I've heard in this thread.