Big Game Partner Plus 2-Man Ladder Stand....lots of room,padded seat and back rest,padded rails fold-up seat and folding Gun Rest.Its gonna take 2-Men to put it up also!

If you are taking a seven year old I would go with a pop up ground blind,they can stand up and move around some when they get bored.On public land you can take it down fairly easy and take it home.

I own a Dicks 2-man. Dicks carries 2 such stands, one has a full platform under the seat and the seat can fold up; the other just basically has an oversized foot rest, and there is no platform under the seat itself. I'd make sure I was getting the former kind.
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I've been placing ladders on public land for 5+ years. I chain them up good. Lowes (& others, I'm sure) sell heavy-duty cables fairly cheap, and can be used to secure a stand pretty thoroughly.

make sure you get one with a guard rail that folds up. It can be used for safety and for a rifle rest.