Hey Jen...Only 10 weeks..YAY!
The bus transportation is pretty good..there is usually a bus every 15 or 20 minutes..sometimes quicker and sometimes slower...but you do stop at many stops..
The campground is HUGE!
So if you wanted to explore a lot..which I do suggest ..

..and not walk everywhere..the you should call and reserve the cart.
Also since it is June and it is HOT...I think a cart would be great..especially after going to be walking at the parks all day..
It will probably benefit Joel and you guys also..
You can take the cart to the marina in the mornings and park and charge it all day while you are at the parks..and then that way when you get back at nights it is waiting for you.
I would suggest it..if you plan on staying at the campgrounds for a good amount of time..which I think I know you said you guys would for breaks and meals and stuff..
Have fun and take me and Maggie..