Pull thru sites is your best option but it not you have a couple of options.
1. If you backing skills are good just leave the dolly connected and back into the site, disconnect when the dolly is at the end of the parking area then back the coach in as far as possible over top of the dolly. Might want to practice this a bit to find the stopping point before the coach rear axle contacts the dolly.
2. Next would be to connect the dolly to the Mariner, use the Mariner to back the dolly into place then pull the coach in.
3. A variation of #2 but park the dolly under the front of the coach.
4. If the site is long enough just park the dolly anywhere.
5. Park the dolly in the camp ground over flow with a good lock on the hitch or a wheel lock.
If you haven't already get a hitch on the Mariner. If you body is up to it you can also man handle the dolly into a corner of the camp site also. Under the coach as far as possible is probably best to get it out of the way.