My suggestion would be to go with an articulated bus. But the problem there will be getting into campgrounds. And you will have to have a 2nd driver for your car.
Seriously, lose the "play area", get a tent for a play area and get rid of 3/4 of the kids' toys (that will include your toys as well). You have to learn to live within 270 SF of floor space. Before you do this full time, have you spent anytime RVing? This is not a lifestyle for everyone.Get a cheap, SMALL RV and go camping for a week at a time in all types of weather. Better if you can be in it for a month at a time.. even thru winter. Cook every meal, do not eat out during your "test" phase. This is our second time at full-timing. First time we spent 17 months in Chattanooga campgrounds in a hard sided pop-up (2 adults, 2 kids, 1 large dog, 1 tiny cat). Close quarters is not something every marriage can hold up to. You can and will get cabin fever. You will get stuck inside for days (weeks) at a time due to rain and/or snow. And then there are times when the flu bug goes around. It's really worse in small cramped quarters. You can forget about "privacy". You really don't have any. And the whole campground will know when you and your hubby are "intimate". Split your bathroom. That way a shower can be taken when someone is "homesteading" in the toilet area. Rubbermaid totes make good kiddy bathtubs (We've been camping since 1979... The girls were born in 1986). If you plan on using the internet to do business over, you will have to have a good, steady connection. That means a sat dish set up or you are in campgrounds using their WI-FI. I can't connect about once a week on average. It was hit and miss last week during all the snow. If you can, try for warmish places during the winter.
I will never go back to a brix-n-sticks house. I've had four houses over the years. While I like houses, mostly because they can store all my books... which I no longer have, I dislike being owned by a house. We started full-timing again back in the fall of 2006. We were living in NC at the time. Since we moved into the RV, we have lived in GA, FL, NC, TN, NM, & TX. Our RV is a 22 ft long Class C. One of our daughters is living with us since we came out west. She was supposed to be living with her sister but her sister's boyfriend "couldn't live in the same house" as her twin (jealously and he's an idiot) so she's with us. Want's her own skoolie too (with a back porch like Smitty's to put a rocking chair on). She gets the Class C temporarily until she can get her own skoolie once we move out.
Stacey has a bad case of "let's go" like her parents.
She loves this lifestyle.
The kids were homeschooled (5th/6th grades while full-timing) thru a TN umbrella school, our "home" state was/is TN and if you homeschool, you must be legal in your home state. For TN (and for many states) that meant we had to be in TN (Chattanooga) for 2 & 3 day SAT's for grades 3, 6, 9, 10, 11, 12. My kids did the Stanford Achievement Tests, not the dumbed down state tests. If they had scored poorly on any one of those tests, they would have been forced to attend public school (my kids scored in the top 10% of the country). Homeschooling is not a cakewalk. It involves alot of work. Get an umbrella school even if you aren't required to. They keep all the paper work. My kids have high school diplomas issued thru Family Christian Academy (our umbrella school), not GED's.