I currently park my TT on a narrow side of my house. I have been debating extending my driveway along the opposite side of the house (quite expensive) to park the TT on when not in use, but now I am ...
We parked our TT on the back lawn or the driveway for 20 years and it was never on the grass long enough to kill it. In fact our gravel drive is starting to grow grass where we parked the TT. last year we got a MH and I took it around back and parked it on the grass for a few weeks. Only you know what your back yard will do when you park on it. If it will turn into mud when it rains you may need some drainage to go along with the gravel.