Hi @rob009 . Another "Rob" here.
In addition to what has been suggested so far, that type of equipment, especially the batteries, can get pretty heavy, so, aside from wanting something durable, you want something that carries the weight well on your back. Find something with a good, supportive hip-belt so the majority of the weight is distributed to your hips, rather than pulling on your shoulders.
Trust me n this, I know of what I speak. Last September I went on a Paw-Paw picking excursion and used one of my lighter weight packs with no hip belt. I made this choice so I wouldn't get juice and aroma all over my "good" day pack. Well, Paw-Paws can get pretty heavy after filling my 20L pack. By the time I got back to my Jeep, it felt like my shoulders would rip out of their sockets.
I am a fan of the Osprey Stratus line. Heavy fabric; suspended mesh back panel; good, supportive hip-belt.
Good luck in your search, and thank you for the trail maintenance!
one or more gifts or other benefits from the co-op.