In my opinion, being a rookie operator, wanting to cut trails in steep terrain is trouble brewing. Especially with a dozer or CTL. One wrong move and one track crumbles the shoulder of your new trail and slips off, basically your screwed. You better hope you have good friends with a machine to come pull you out.
Mini ex's are a bit more forgiving, if you do slip off the trail, you can at least wiggle your way around with the bucket and boom and get back on track. I would look for a mini ex that has the longest tracks for stability, and perhaps get proper cab protection built for it, so when you do roll it, you will survive if wearing a seatbelt.
I live in BC Canada, we have our share of steep slopes, those silly rocky mountains make work challenging. :beatsme