Thanks everyone for the replies. I Decided to look around for a rental place and see if I could try to get a rear blade for a day just to try it out. I really don't want to be too invasive by getting a bulldozer or excavator to make the trails but I will look into my options. I don't know that the 7510 would have enough power to bend a blade, but that is the last thing I would want to do especially if I rent or borrow the implement. Based on the opinions here at this point it sounds like I much better off to fill the really bad spots with gravel or dirt.
GaryE, I think my land is just as rocky as yours, I live near Bangor. I actually have about 8-10 inches of topsoil (mixed with rocks) in the yard and a bunch of gravel under that. In the woods there are rocks and boulders all over, most of the trails don't have enough soil to dig a hole without some HEAVY equipment. Thank you all for sharing your experiences.