Under the seat would be about the best place but cut down on the rear storage. But that's no biggie. Whatever doesn't fit could go in the front.

 

The King quad 750 goes with the battery under the seat. It has a little semi waterproof storage bin in the front with and another storage box under the rear fender on the left side, exhaust is on the opposite side. That storage box under the front rack of the Sportsman is very nice, really gives you a lot of built in storage.

 

A lot of times I put my jacket in my front box in case it cools off later in the day. There's usually a machete in there, and I put my wallet and keys in there so I don't lose them. My wallet fell out of my back pocket on a ride several years ago and I learned my lesson. And I get a lot of stuff in my rear storage compartment. One day I put some Powerade bottles in it to see if they would fit sideways. They did but I don't know how many would fit in there. That's what my cooler is for, but the rear storage is the biggest of any ATV I've had so far. Even if they put the battery in front of it that would still leave room for a decent sized box.