I also own 2007GMC3500 EB which I bought with 5K miles on it. Since I bought it in April, we drove over 7K miles visiting 14 different national /state parks (Shasta, Yosemite, Crater Lake, Banff, Jasper, Lake Louise, Orcas Island, Lopez Island, Lake Wenatchee, and others) in both US as well as Canada over the summer with my 2 girls.
The layout I bought turns out to be a perfect model for us. We were a bit concerned about side face seating (2 long dinette allow our kids sometime laydown and sleep when we leave super early in the morning, and neighter of my kis ever had a motion sickness from facing sideways)
We never cooked inside when we owned a travel trailer so we knew that we didnt want the cooking system. We never used the sink either in our trailer so we knew we would be just fine without it. However, what we found was, unlike the travel trailer we had, we were on the go and quite mobile. I wanted to have an ability to at least boil water to make quick instant noodle, coffee and such at the rest area. All other formal meals are typically prepared over the campfire. For this, I added 1500W inverter to the van and just installed an automatic transfer switch last week( Thanks Dave for the tip). The setup we have in place is super practical and been working out great for my purpose (family camping vehicle). I too bought a Mr.Buddy heater (gift) but never got to use it so far. Even when we camp in 30s (Jasper morning), we never felt it was needed.
When I need to drive on off-road, it will be most likely without the family so I take my truck.
I get between 15 and 18 MPG depending on the road. Our trip to Canadian Rockies got us about 18MPG while the trip to Yosemite was a bit over 15MPG. This is by far better than what I got pulling my trailer (10MPG).
Other benefits of this setup:
- I park the van inside the garage (height is 7'5)
- I pay the passenger car rate when I take it on Washington State Ferry to get to islands (under 20', 7'5). I know it is actually 20'4 but they dont seem to care based on my 4 trisp so far)
Anyways, feel free to PM me for any specific quesiton you may have.