Also in NJ and just mulched my potatoes today, mix of straw from last year and then leaves, again from last fall. The straw has enough structure still that I think it will prevent the leaves from matting, and neither has any nitrogen content to speak of so it should not heat up on me. Going forward I expect there will be some relatively fresh grass clippings going in there as well, but I think even then the mulch is going to drain well enough not to turn into a hot compost pile.
I am using a couple of cement reinforcing panels ( a bit smaller and quite a bit cheaper than
cattle panels) as a container around my potatoes - which means real potential for it to be a compost bin if I get the mix the right kind of wrong. I am not really concerned, since my intentional compost pile where I was trying to get it to heat up never got with the program. Of
course, this means I will be cooking my taters in record time