Paddock enrichment?

I have a really really smart ex-ranch horse. He’s incredible, and easily smartest horse I’ve known.

Where I live, barns only have paddocks, except one. Two year wait list that we are on

He lives out 24/7, has a show horse turnout buddy at night, but it’s an acre paddock and he’s smart. I’ve given him food based toys but once he figures them out he’s done. He’s not as food motivated as others I’ve had.

What about something like an obstacle course?

Of course in our teaching sessions (we teach each other - I do not train him!) I mix things up and work with him as often as I can. That helps a ton.

But I’m in the south and have an autoimmune disease that will NOT tolerate heat. I can get close to passing out pretty easily, at least on bad days. So only much I can do at present.

Advice for how to keep this fabulous but ever challenging animal happy?