... and here I thought the point of camping was to get away from all that pavement and sleep on something softer than my office chair. Turns out nature's mattress is just a warranty claim waiting to happen. Better to ease into those stretches like you're testing a used car, not like you're trying to prove something to a bunch of pine trees.
Go for twists and forward folds. Tbh, when you said your back is tight from the ground, I get it. Start with cat-cow to loosen up your spine. Then, do some easy twists like lying on your back and letting your knees drop to one side. Hold pigeon pose for a bit to help your hips. End with legs up the wall so your back can flat out rest.
Ruby's advice is helpful, but starting with twists might not be best for everyone. I've found they can make lower back tightness feel worse if you jump in too fast. Focus on slow cat-cow moves and the wall pose first to ease into it.
My buddy tried to power through twists last week and said his back locked up like a rusty gate. Had to tell him to chill and do the cat-cow thing for like ten minutes first.