Personally, I would not do this as a car spotted hike.
I would hike up the lovely Gale River Trail, drop my bag at the Hut to tag Galehead. Back at the Hut, I'd eat lunch to fortify myself for the haul up S. Twin. At less than a mile, this little jaunt is likely to require some stamina. At the summit of S.Twin, I'd take a nap and stretch my legs before sauntering the easy 1.3 over to N. Twin, (make sure you go to the viewpoint), and then 1.3 back to S. Twin, returning the way I came, knowing full well what was ahead of me.
I would seriously hesitate to expect someone who has never been on these trails before to tackle North Twin Trail. For one thing, the stream crossings are difficult and will require wading bootless. Another issue is that other frequent hikers expect shamples to find and follow the bushwhack, without knowing if shamples is comfortable with being off-trail. I know the North Twin Trail has a new adopter ::waves:: but it is generally one of the most unpleasant trails in the Pemi, if not the entire Whites.
IMHO, the North Twin Trail is not a good way to start a day of hiking. It has stream crossings for which you must remove your boots, a virtually-required bushwhack right out of the gate, the grade is boring, the treadway muddy, and the definition obscure. If a car-spotting hike is etched in stone, I would recommend descending N. Twin Trail when the magnetic lure of the car can draw you along a sketchy and unfamiliar trail. You can wade through the streams, without leaving the trail, arriving at the car with wet boots as the only bad memory of the day. If you ascend North Twin Trail, your memories may be much worse...
Just my 2 cents (former adopter of North Twin Spur 1993-2000)