My wife and I have been traveling with Golden Retrievers for years in our FWC and also an older Airstream. A lot more fur than a yellow lab. For starters, all the vehicles we own have tan interiors, including the '99 Ford Superduty Extended Cab. The dog/dogs ride behind us with the seats folded down. We lay down a piece of foam and cover it with brown army surplus blankets we picked up at the surplus store. We shake the blankets out periodically and also use a wire bristol dog brush to clean the upholstered "bolster" below the cabs rear window. Inside the FWC, we put old flannel sheets or "dog" towels down on the benches. They can be washed and shaken out. On the floor of both the FWC and the trailer, we lay out more of the brown/tan surplus blankets. They are dense heavy wool, provide insulation on the floor and can easily be shaken out to remove dog fur, grit, dirt and sand. We've even washed them on occasion.
Beyond that, we keep a small broom handy for the camper floor and, most importantly, we don't ever where black fleece. It's the price we pay for happy demeanor, devotion and general good will.
One of the advantages of your yellow lab vs a golden is that they probably dry off quicker after a swim.
Good Luck.
TK