Originally Posted by shane_the_ee
I think that's gonna be a little hard to a) get into a national park as the OP implied and b) pull with a vehicle capable of seating 2 adults and 4 kids with the kids in various sizes of carseat. Particularly if they're going to be doing cross-country road trips as also implied by the OP.
With 4 kids the OP needs a big truck and a big trailer. I know the OP is thinking of fitting into small sites but first the OP needs to fit his crew into the RV and TV. Due to family size the OP has crossed the small RV threshold.
6 people on a 20' RV is cramped. NOw if you only camp in smaller forest service CG going small maybe doable. However the OP must expand his vision and realize the RV can be used whenever the family must travel over night.
That means going to visit family, take the RV. Going to an amusement park, take the RV. Going to explore another city. Take the RV. Going to the beach, take the RV.
Once you realize there is more to RV'ing than forest service camping, you will not want to base your size solely on FS CG's.
You will also want to use private CG's on occasion, Also state parks can have larger sites.
You may sometimes use your RV strictly as a hotel room. In which case location of CG quickly becomes more important than type of CG.
With a small RV you will need to convert beds every morning and evening.
You will be pressed for storage space. With a larger RV like the one mentined.
The RV becomes more of a rolling condo. Everything you need is always aboard the RV. Add a few perishables and you are off!
Once upon a time I was in the OP's shoes, I had a diesel Excursion pulling a 31BHDS rear bunkhouse RV. It was a fantastic combo.
In today's world I'd look for the same TT and a Full size van to pull it.
With the right set up you will enjoy camping and travel via RV whenever possible. With the wrong set up, the experience will not be as enjoyable and you will not use the RV as often.