Nick,
Try looking at an Isuzu FRR/Chevy W6/6500 cab overs (all basically the same truck)
- 200hp turbo diesel
- Allison auto trans
- Great turning radius
- 19,500lbs
- Air assisted hydraulic brakes
NPR/W4/4500 are a little too weak for chips and a large chipper.
I have a FRR with a 14' bed and tow a 8,500# Morbark chipper with no problems. (yeah, fully loaded with chips it's in the CDL territory)
I've built about a dozen dump bodies on Isuzu/Chevy cab overs (for both woodchips and grass). They are bulletproof, but don't get a standard trans unless the guy knows how to use it . . . we learned the hard way and converted all ours to autos.
A 14' long, 50" high bed will hold about 6 tons of wood chips.
(we've used W6/6500 Chevys with 30 yard bodies and hauled 10 tons of grass and a large vacuum for years with no problems.
NY has a different requirement than NJ for CDL.
In Jersey CDL is under 26k, or combined truck and trailer under 26k (but the truck can't be under 10k). Also in NJ you don't need a CDL for air brakes if the truck is under 26k.
Whatever you chose make sure you have a good electric brake controller (especially for those quick & panic stops).
While at the ISA convention in Pittsburgh, most of the chip body fabricators told me they could add a body (hoist & labor included) for under $12k.