Your best bet is a Older , calmer lab . Even then 8-9 hrs is along time. some of my experience as like you we came from a doxie , camp alot along the east coast and some times at bourne scenic park or bay view.
First year is going to be real tough as puppies need alot of frequent attention.
They are energetic and need alot exercise. gigi is going to be 1 and she goes to big dog park on the weekends ,gets walked every day and we even send her to day care if we cannot take her out due to weather or if we are sick.
She does loves to camp, they are fun. She last summer camped in the cape , new Hampshire, poconos , maryland , outer banks of delaware and was a road warrior.
we spent a lot of time on puppy social , training to get her to be boarded when we take our kids to theme parks in our travels like hersey park.
your parents will have issue, my mother in law watches her with the kids but she is used to having labs and spaniels all her life . Even then i take her to the dog park for an hour to drain some energy.
We have left her unattended for 7-8 hrs on few occasions but then again run at the dog park and let her rest. You put a young lab in a crate for 8 hours, you are in for a few hours of tremendous out burst of energy for the next 2-3 hrs.
On another note a young lab is not suitable for a closed on top of each site campgrounds in Cape Code. I prefer to take her to state parks and campgrounds where we have more space and alot of woods/water features. She loves to run , swim with the kids and us. we look for a more open campground because of her.
The Lab might not be a right breed , a more sedate breed might work. even then 8-9 hr thing is a think i will be worried. It must be a doxie thing as our doxie did not care one bit. He loved to camp , but went to bed in his crate when he wants and would just hang by himself all day if left. He needed people rarely but really never cared. The lab is just the exact opposite. Plus you could use a puppy pads and the quantity of pee is manageable. gigi at 8 month is solid enough that we leave her alone in the camper. the doxie would just go to his crate and sleep when we go for trips. not gigi.