Screw it, just clearanced the terminals with a dremel. Here's my write up:
Installing a Battery Tender Jr. on a '09 Polaris Sportsman 500 EFI.
When I tried to get to the battery the body work was in the way. I decided I didn't want to hang the battery by the cables to install the battery charger. It looks like you have to have a two-man crew to install the battery, or be willing to dangle it by the cables. I suppose putting it in you might be able to pry and prod it in at an angle to get it wired up but I didn't have the hands or the patience to do that. Dremel tool to the rescue!
Pic 1 - 7.5 amp automotive blade fuse comes with the BTJr.
Pic 2 - Pretty short cable on the ATV end, maybe 2ft. (it also comes with a short aligator clip cable, not pictured.)
Pic 3 - Can't reach the positive terminal without pulling the battery out. Note that silver loop (middle of battery) is a factory bungee hold down.
Pic 4 - There is probably enough room to tilt the battery back (toward the camera) and lift it out, but then you'd be hanging by the cables. bungee was unhooked by me before the pic.
Pic 5 - Dremel to the rescue! I clearenced a LOT less than this on the other bike, just enough to get a screwdriver in there. Seat seems to sit fine, bodywork seems to be as strong. I will be watching this as it ages though, may need to reinforce it if it starts to show signs of cracking around my handywork.
Pic 6 - BTJr installed!
Pic 7 - Just enough cable to come out behind the seat. I ran it under the bodywork so the seat doesn't pinch. Zip tied it to the wire harness there.
Pic 8 - It is just the right size to jam under the rack a bit. I think it will ride fine and quietly.
Pic 9 - Back to sleep for another few weeks until it's warm enough to ride in comfort here. The 10' cable on the plug end was probably long enough to reach the wall, but a cheap extension cord made it easier to unplug to walk around in my tiny garage.