You're never 60 miles offshore even on a straight line course between Montauk to Cape May.
Now if you run the coast and stay close in you only add about 22 extra miles to the trip. From 195 nm to a distance of 217 nm. Or about an extra 3 run hours at 7.5 knots. So either way you only need a day and a half to a maximum two day weather window. Not 3 full days.
Plus you have a number of places you could go into if the forecast took a turn for the worse.
Drinkenbuddy: Here are your inlet options along the southern coast of Long Island and the coast of New Jersey.
1. Shinnecock Inlet (31 miles or about 4 hours west of Montauk Point) The inlet should not be attempted without local knowledge because of frequent changes in channel depths. Tidal currents through the inlet can be dangerous and caution is advised.
2. Moriches Inlet (44 miles or about 5 1/2 hours west of Montauk Point) This is a shallow entrance from seaward to the deeper Moriches Bay. The jettied entrance is subject to frequent change. Mariners are advised not to attempt to navigate this inlet at any time without local knowledge.
3. Fire island Inlet (28 miles or another 3 1/2 hours) west of Moriches Inlet. This inlet is subject to frequent changes... Mariners are warned to beware of extreme tidal turbulence especially during times of tidal change and should seek local knowledge of the latest conditions before attempting to enter. Navigation of the inlet is difficult even with relatively calm seas and can be extremely dangerous. During heavy weather, the entrance usually is obstructed by breakers.
4. Jones Inlet (12 miles or another 1 1/2 hours west of Fire island Inlet) The inlet is used mostly by local pleasure craft and fishermen and should not be attempted without local knowledge due to constant changes in the channel.
From this point, you will be crossing about 50 miles of open ocean working your way toward your next safe haven, Manasquan Inlet in New Jersey. If the weather does turn nasty and you are able to make it through the inlet, watch out for the railroad bridge. It will lower when a train approaches, but you should have plenty of notice if the current is not too strong.
Then, it is just a pleasure cruise down to Cape May. If things get snotty on this section, there is always Barnegat, Little Egg and Brigantine Inlets to explore.
I realize that your plans are to do this voyage when your weather window allows. The weather window for Montauk may be completely different from the south Jersey coast, so I would try to choose a weather window where all circumstances are favorable. If nothing breaks on your new boat, you should be OK..