I don’t think I’ve ever read anything about tree houses, but you don’t have to tell a 7 year old that a tree house would be cool. They’ll already be climbing the trees anyway, bringing up a convenient plank to sit on, then turning it into a pallet you can sit on together, then to cover it with a roof, and when you find our the rain still blows in sideways with walls, that’s childhood to me.

I spent years on that treehouse and then it burned down :(

Check your local permitting - there are often many “structures” that don’t trigger audits or permits but are still usable - outdoor kitchens, tents, etc. a treehouse may just be one option.

Terrifying prospect

Maybe a sheet metal "band" around the trunk, several feet off the ground, would be enough to stop the scorpion from being able to make it to the treehouse. If the surface is smooth, the scorpion's tarsal shouldn't be able to find purchase.

Like a 12 to 18-inch wide band of smooth stainless steel or aluminum wrapped around the trunk.

Scrape x-inch bark off > apply metal mesh > 100% silicone sealant > butyl tape > wrapped aluminum > lock in with stainless steel hose clamps. Could even get a design lasered into the metal which might be cool.

Kind of like this from Reddit, but with those add'l steps: https://archive.is/yHYdj