I'm sort of similar, and I've used a few over the years . They used to be really expensive, but most of them are very affordable now.
My current main trailcam , can be watched live , and moved around , from my phone . It's got an internal battery , and a solar panel . It only cost around £130 ish from amazon , but I looked last week , and you can buy the same cam for less than £70 now.
It's some of the best money I've ever spent .
I'd like one of the live cams that track movements, but I couldn't find any portable ones . I don't reckon they'll be far away though.