Andy’s reply is spot on, both regarding powering options and long cable techniques. I know Chris Watson uses 200m cables on occasion and he says he hasn’t noticed any issues stemming from this. If you go this route make sure you cover your XLR connectors and possibly hide the cables around your mics so that wildlife doesn’t think it’s snakes or the like.
I do a lot of drop and leave overnight recordings, and on top of what Andy mentioned I also use a Cinela blimp that keeps my mics dry even in heavy rain. I also leave my recorder bag in a dry bag and tie it to a tree or big rock. The biggest problem with unattended recording is that you never know what you’ve recorded. More pedantic recordists will never do it, but I’m fond of it and I love listening back to hours of overnight recordings (sort of like opening presents, youy never know what you get!).
I’ve always been wary of wildlife interfering with my rig, but so far I haven’t had any problems. I have recordings of boars coming really close and baboons bumping into the tripod, but it seems like my rig was never that interesting for them. One thing I always avoided is keeping food in my recorder bag, since it would definitely make them curious.
One other thing I should mention is you don’t need a really expensive rig for long recordings. On occasion I will leave my Sony D100 out overnight as well, and I think it can easily do a 20-hour session on 4 Eneloop 2500 mAh batteries. It also sounds quite good for a small handheld.