Two peops and a 70-pound German Shepherd would be cramped inside a teardrop. My 48-pound Samoyed and I are plenty comfy in a 6'wide. But my teardrop doesn't have cabinets.
You also need to be mindful of your pup's ability to get in and out of the teardrop. Coincidentally, this past week we were camped next to two elderly German Shepherds, both of them suffering severe hip problems.
My Honda Element would be plenty roomy for Gidget and I'd feel she was safe in it by herself where we camp (where the black bears don't have a history of breaking into vehicles), but she'd bark if left alone all night.
Is your tow vehicle a pickup or SUV?
Perhaps the best option would be an attaching side tent that you could crate your pup in or secure them via a leash to the teardrop (leaving the door open on the teardrop so you have constant access to your pup and vice versa).