Never actually done the tailgate there but if you do I would consider 2 things.
1) make sure when your leaving you don't wind up back on rte 1. Waxy's is in the neighbourhood behind the stadium and you will be able to get to exit 7 on 95 if your going south and exit 8 if you go north. Don't let yourself wind up back on rte 1.
2) the shuttle might have to use rte 1. If that's the case it might actually be quicker to walk to Waxys after the game. There is path behind bed bath and beyond you can use that will let you out a few blocks from Waxys. If you do it right the walk isn't much more than a mile-mile and half. You should be fine taking the shuttle in as long as it not the very last second. Check with them too they might be allowed to use the access road.