In my opinion DIY is more satisfying, but a WHOLE lot of work- obviously. I guess I would consider a mixture of resources having done this similar thing a time or two.
Perhaps consider initially bringing in a Forestry mulcher to knock out an inner area access trail for you that allows you to reach the back areas, yet still leaves natural barriers to keep out trespassers. Then you can work on finer details with your time and equipment. If you find the task remains daunting, you can always bring equipment back in... The nice thing about a mulcher is that the end result is just mulch as opposed to piles of knocked down trees that might get in your way. (Dozer on a tear would be cheaper though to be sure.)
This big guy here could make short work of a basic access trail. There are also skid steer mounted units that have done great work on our place a couple of times.
Enjoy your new place! Stay safe and have fun.