i would say yes, the mud hole starts less then 10 miles off the beach, but to hit the wrecks of the mud hole, and the deeper water, will be more. how much more im not sure, would have to check over the charts, which i dont have handy right now.
going out of the manasquan, i think the oil wreck was like 15 miles or so, which sits in some pretty deep water.
best advice, get some local charts, and also one for off shore, which will give you plenty of stuff with in your reach,, with nice weather of course.
i have a 21' WA and was quite suprised when i reached the mud hole to find 7-8' rollers when 3's was called for. didnt have any problems with the roughness, but didnt stick around long either