Only thing I think of when I see people going this far in the dinghy is how much it would suck to have an engine issue. You could have to row a long way!

I've never had a dinghy engine fail on us, but its always a possibility.

If you are willing to take that risk, then its certainly doable in the right conditions. But really no reason not to just move the big boat. If you are concerned about leaving the mooring and want to hold it, you could always leave the dinghy tied (locked preferably) to the mooring ball after paying for the mooring.