Ok, I suggest that we start at Galloping Hill Inn. Convenient, enough parking, and a great grilled beef/pork dog. Then head down to J's. From there we can either go to Jerry's and Tommy's; or we can skip these places in favor of Dickiee Dees (another Italian Hot Dog place) and Tony's, if they're open. If Tony's isn't, we can hit JJ's, another popular truck known for very spicy chili. Or we can hit both the Elizabeth places and the Newark ones. I think it would be a good idea to hit Amazing Hot Dog in Verona, since that would give us at least 2 new places and maybe 4 if we hit Newark. Again, all of these places are fairly close and accessible from the Parkway. Amazing Hot Dog is actually on the same street as Dickiee Dees and JJ's, but a few miles away. Newark is a few exits away from Libby's, which would be a good substitute for the Hot Grill.
As for Manny's, it's only a few blocks away from Syd's, which is between Linden/Elizabeth and Newark. We can do a lot of places in a little time. It might be a good idea to hit all of them. You can pick and choose what you want to try, or share.
A rough outline: Galloping Hill Inn, south to J's, a few miles to Elizabeth, Jerry's/Tommy's (optional), north to Syd's/Manny's, north to Newark, Dickiee Dees/Tony's, JJ's,(optional) which are mere blocks from each other, west a few miles to Amazing Hot Dog, north to Libby's. And, if anyone still has room, a few miles away to Rutt's Hut