So we have 2 basset hounds, so they aren't as tall as a lab, but we use a pen when we're camping with them, instead of tying them up (they aren't fans of being tied up). We originally got the pen when our younger dog was a puppy, to aid in housetraining, as it goes with her crate. But now it's just handy for camping, and the pups are happy in it.
This is the one we use, looks like they make it up to 4' high, which may or may not work for a lab, depending on the dog. You can also attach multiples together to make it larger.
https://www.amazon.com/MidWest-Exercise-Pen-30-Inch-Black/dp/B000H8YTJIAlso, obviously, we don't leave the dogs in the pen if we aren't around, and they sleep in the garage area of our toyhauler at night.