Rear storage box

Tried searching the forum and couldnt find a good thread of what I was looking for.

A concern i have is being able to get to the battery if needed. Im not sure if mounting a box will make this difficult

Im looking for a small/ low profile storage box for the back of my Rancher.

Something bigger than the Ammo Cans, but not as big as the rear seat boxes and huge trunks.

Have been thinking about something like the Tamarack front storage box. (right now thats what im leaning towards) ATV STUFF Front Box

Will be used trail riding to store supplies, and will also be used at my familys farm for storing gloves, clippers, tools, etc.

Would like for it to be water resistant/ dust proof.

Anyone have anything they found that works well? Doesnt have to be made for an ATV, but would like to keep it under $100 if possible.