[quote]Questions:
I would like to insulate it further, both for winter and summer. It does get hot and cold. Other that fiberglass batt insulation, what would be good, and low cost? [/quote]

Other than burying it? Lattice work and vine overgrowth for sun shade. Expanding foam insulation sprayed in to the doors etc.

most of us skoolies use CERAMIC insulation www.hytechsales.com/index.html
ps. i have an aerostar too. i screened over the windows and put in a 6inch 12vdc rotron fan for ventilation. mine is still roadworthy.

Lived in a 1963 GMC stepvan for 6 years in the early 80's ~ Until I blew up my 3rd engine and could not get it rebuilt and back on the road. Purchased running, in good working order, with newer tires and year tabs for $500 cash.

We insulated with 3 inches of recycled/salvaged foam in the walls and ceiling and more on the floor under salvaged carpeting.
Installed a large sliding side window and two ''pop- up'' roof vents; tongue and groove ceder paneling and spray painted the cab interior. Built on a back porch that folded up to hold 3 bicycles, jerry cans for gas and water and two large potted plants.

Built in a raised bed with clothes storage underneath that folded out to a double.
Had room for bookshelves, a small 2nd hand boat heater, and many of the amenities (pets, plants, kitchen set up that fit on the engine cover when in use...artwork, musical instruments and Camping Gear !)
Being on the short side... I was able to stand up inside (5' 6'' clearance in the center).. Most of my friends only needed to walk with their knees bent.
All of this ~ For a total out lay of less than $800 start to finish - with a Lot of the work done with friends' help, a lot of creative thinking and scavaging/recycling/reclaiming. It fit EXACTLY into a compact car parking space !!! The sliding doors helped .... we could park it anywhere !

Took the beast from Seattle to NYC and back by way of New Mexico - Twice.
Found that we could sleep 4 adults, a St. Bernard, and 2 cats all inside (in a pinch) - mostly it was just two of us and the pets....
I miss my old ''beast'' ~ but it still lives somewhere in Seattle... Some one bought it and it was last seen being driven near the U of W.

Hey, some great suggestions and stories.

Bury it: that sounds like perhaps the most efficient method in terms of results and effort. A van might even withstand the side pressures, if perhaps the windows were boarded up, or made sunken light wells around them. I will have to think over that option for my residential neighborhood as far as looks. I know you guys are specializing in this in other threads, but can the van stay above surrounding ground level, and just have a dumptruck deliver a mound of dirt tall enough to cover the van on all sides?

Vines overhead for shade: that sounds like what I may do for summer heat abatment. I expect leaving a couple of feet between the vines and the van will allow cooler air to circulate. Perhaps some bamboo poles, string and bean vines...

Spray foam: that sounds good because of being easy and airtight, high r-value. Perhaps chicken wire stapled to the upholstery would help it stay in place.
Questions: is this a do it yourself project or contractors? How much would it cost to insulate a minivan this way (walls and ceiling, not floor)?

Ceramic Insulation: if I understand Steve's link specs, this is hollow ceramic microbeads which are added to paints. Their benefit is primarily reflective in nature. Paint on the outside to reflect heat out, pain on the inside to reflect heat in. Heat/ cooling savings up to 30%. Cost about $15/ gallon for additive. Sounds worth doing. What savings have you realized?

Mattress foam, 3": that sounds sensible. I am leaning towards that, even perhaps new.

I had also considered, secondhand mattresses/ using their non-spring materiel; carpet underlay foam; secondhand carpet; wool thrift store or army surplus blankets.

Someone mentioned pillows, and I remembered I bought synthetic pillow filler, @ $7 for a box (Walmart), might be enough to cover one van wall about 3" thick. So, for 4 walls and the ceiling, I might need 5 boxes =$35. I would need to add a barier on the inside for best effect, right? I.e., plastic sheeting, or plywood sheets, etc.
One idea would be to fill large plastic trash bags with the fill, then flatten them out into rectangular insulation panels, say 3"x3'x4'. Then I would just hot glue, tape or staple them in place in the interior.
Would the R-value of this method be comparable to fiberglass batt insulation?

Long-term living in a Van: those sound like great times in that old 60s van. Something about a van does feel like it is the right amount of space for a person to live in. You just feel comfortable camped there. And with all the windows it has, it could practically be a greenhouse! A few indoor plants would definately improve a van.

Camoflaging a van: that sounds cool to paint a van/ camper with the scenery where it will be setting. It's not illegal for a home/ shelter to be in visual harmony with the nature around it.
related: back in mechanic school i had a classmate who worked for the army and he got his vw bus painted in camoflage by the same folks that do the tanks, etc. It looked neat, but of course you could paint with more peaceful/ nature connotations.