With the weight of the wood, box and chipper let alone the base truck, you'd be foolish NOT to get a truck rated between 26-37K, with proper air brakes, a jake and either a good auto or a 9spd manual. I understand what you're trying to avoid (costs and the DOT) BUT you know you'll be flirting with or outright breaking the limit otherwise, probably often and it's only a matter of time until you get a nasty ticket (if you're lucky) or sued for running overweight and under-equipped while accidentally killing somebody. Lawyers would have a field-day with that one (so you better have awesome insurance which may NOT cover you while operating illegally).
I despise the EPA and don't agree with a lot of the Gov't intrusion into our lives, but many of the DOT laws are there for a good reason. Please think to your crew's lives and other peoples who will be encountered by your truck(s) on a daily basis at highway speed. And think of the idiots (who I agree should know better) that constantly set themselves up for death by being too close to big trucks at highway speed. It's still going to be their fault (most of the time) but the rules change when one of the incident vehicles is near or beyond CDL territory. The idiots almost get a free pass.
Hel I'm looking at either a 5500 Ram 4x4 or a freightliner/int'l/etc single axle crew cab with a 5th wheel plate and a GN ball. I'd only tag it to 39K and be able to do everything I ever want to do, but legally. And yes, I would have to acquire my Class-A (farm use only), have a DOT health check, etc. I don't relish any of those things, but I don't want to accidentally kill anyone and be financially ruined for the rest of my life.
I'll get off of my soap box now and sorry if I pissed you off.