I agree with MossRoad. If you are going to be cutting brush 30 hours a week, you may be happier with a mulching head on a tracked skid steer, like an ASV RT-75, if the slope isn稚 too bad. If it is, a 1445 will take you to 25 degrees or so, or an 1850 to 45degrees, but they don稚 have the weight that a skid steer has, so they aren稚 as good at earthmoving for trails, but better at floating over soft ground.
My 1445 with a 6 brush cutter goes through brush faster than a skid steer with a mulching head, but leaves behind bigger pieces, and the stumps are a couple inches high. A mulching head will totally remove the stumps.
Can you help us out? What are you using now? When you say trail, is it flat, sloped, or really steep? Is it mainly brush removal? Grading? Adding base rock? Are they trails for humans? Horses? Bikes? Cars?
All the best,
Peter