I wore a conventional leather tool belt for a lot of years doing my side job of contractor/carpenter. I can tell you I hated that thing when it was hot out. Big, Heavy, and Leather are not 3 words that I want right in front of my crotch. Anytime we'd stop for lunch, taking it off it always looked like I had just p'd myself. Absolutely soaked.
Funny, looking at pics for what I was going to show you I see now, all the big heavy rigs are split with an opening for a tape measure, which I can''t think would be comfortable if you had any gut at all, but at least the newer variety wouldn't be quite as hot as my old one where the to big pockets were right in front, NO AIR....
I've since purchased a web like creation, still has tough nail pockets out front, but close to you the web pockets breath well, and allow me to carry whatever I want in them light and airy. LOML had bought mine for me years ago, and just now gave me a blank stare when I asked where she got it, then perked right up, and said "at a store," batting her eyes..........
I've seen one's at HF that weren't far from what I have, also at Lowes, HD, and Menards, the others just cost a lot more. Look like this one. This was suggested it was a "gardeners tool belt" Mine has pockets on both hips, leaving the front, and back open. Not sure what you know about heat, and the body. Didn't mean to go on about my crotch earlier, but keeping it cooler, keeps the rest of you cooler as well, so open in front will help 80% or better right there.