Hi Ptamom,
Them using you as their tree is great! They go on your back because they would ride on their mommy' back when they were joeys, so they're treating you like their mommy. They fall asleep in your shirt, that means they find you safe. They even come to you in the tent- that's trust.
They run from you when not in the tent-that's curiosity and feeling safe enough to wander.
Sugar gliders are curious, independent, hyper creatures. Not all gliders like to snuggle or ride in a pocket or come when they're called or even explore. Of my five every single one is different. The only one who would hang on me is Luna. Gimli likes to explore. Clare is a spaz who won't come out to play but would play in a tent. Thor won't come out to play, period. Fionn is a total nervous nelly who still hides from me in the cage 3 years after I adopted him. Yet, he will come out and get a treat from me, then go right back into the cage. But I know they all love me because I feed them and give them treats and hold them and cut their nails. And I'm their mom. That's it. Sure, it'd be cool if they all hung in me like the videos I see. But that's just not them, and I'm okay with that. In fact, I've had Thor for five years and in all that time he's only ever climbed on me like twice. But I know he loves me! He just doesn't want to climb on me.
So, I hope my perspective helped you. All gliders are different! But they know who takes care of them.