Sadly there is not a huge market for this kind of product and the choices are limited.
The wildland fire boots are one route (although for me personally they are too hot). They are usually full leather, non-waterproof and stiff. Just google wildand fire boot for the options out there.
There are a few companies that make a highly breathable boot - but they are not for serious off trail hiking (generally speaking) Vasque Breeze, Merrell moab, solomon use to make one but I don't see it anymore. Lowa use to make one as well but demand just isn't there to keep them in production I guess.
I currently use Lowa Innox (non-waterproof) and the older vasque breeze and breeze 2.0 (non-waterproof) for early season HOT weather hunting. I tried full leather boots and LL leather boots and they are just too hot for me.
IF you find something out there post it up, I am always on the hunt for the best HOT weather boot.