Everybody likes what they have.
So, I think an Kubota RTV 1140 would be just right. Not a speed demon, but I've pulled huge loads with it and it has the convertible bed/extra seat. Easy in and out. I predict that if it is going to be for fire fighting you will be hanging hoses, hoes, axes, pumps, water tanks, extra trailer behind, etc. all over it. The Kubota platform has lots of options for adding extras. You would need to have the air intake up high to avoid intake of dust and cinders. It's diesel and HST. Some people think it's underpowered, but one simply needs to understand how to select the proper gear and to drive an HST. I've been able to climb any hill if I could maintain traction.