[Batvette]

For ventilation you could consider putting the fan inside the driver side rear fender area to exhaust air through the vent flaps located there. Or since you mention wanting to get air from the bottom of the car, maybe push the flaps open and pull air from there into the van.

I did a crossflow blower in that spot in my 07. It was completely useless and made a lot of noise. I put the biggest blower i could find in the bezel too.

In my 16 Ive been using a Vornado Transom window blower in the moonroof. With s couple of 2"x2" rt angle aluminum pieces added, it drops in in seconds, and uses just 28 watts at max speed. I created a thread on it a couple of years ago.
Its like a tower fan placed on its side and exhausts or intakes air. If you wake in the mid morning and the van is blazing hot, this blower feels like you turned on the AC after just a few minutes.

Back to the 07, I actually experimented with installing a portable air conditioner behind the drivers seat. I tried several brands, each were about as small as they get, about 14" square and 27" tall or so. On one I converted it to dual hose operation for more efficiency, with both hoses exiting through a tinted lexan window bezel in the drivers side rear window. It had rubber seals and was pretty airtight. Overall it worked pretty well though took up a lot of space, particularly the hoses.
Of course the deal breaker was keeping power supplied to it. They run about 700 watts continuous, twice or more that on startup. I could only really use it with an inverter generator running outside, though i had plans for 560ah of DIY lifepo4 which should have been good for 5 hours fully charged.
The whole thing was too much trouble, i did build one of the 280 ah batteries and 3 1/2 years later its only at around 100+ cycles and working perfectly.

It was nice sitting in the back of the van on a summer day and making it like an ice box. (Something done a lot easier with the 3rd gens factory AC pumping through the floor vents, and laying on the floor. The 4th gen has the best rear AC, they moved the upper ducts from the roof to the top of the side walls. The roof ducts of the 3rd gen seemed to lose a lot of the cold by the time it gets there.)

 

[Batvette]

Thank you for sharing your trials and ideas!
Did you just take down the Vornado and stuffed it somewhere when driving or not using it? Or was it semi-permanent up there in the sunroof?

In your last paragraph, are you suggesting one could just idle the van and run the A/C for an hour or two?

I pretty much kept it up all summer long. Rainfall in summer months is rare in my area. I also have one of those clothes hangar rods walmart sells in the auto dept, couple holes drilled in the aluminum angle, couple snap hooks, I could hang it in back or just toss it on the floor.
Yeah I wasnt afraid of idling for an hour or so. Wouldnt sleep all night like that.
One neat thing about the way the vornado mounted, it blew toward the back at a perfect angle. I just cracked the curtains a bit at the bottom.
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I bought the whole set, less the moonroof cover .fit well and durable. Just a bit of black matte duct tape in some gaps, total blackout.

I tied paracord all the way around the rear perimeter across the hand grabs. Then made curtains, sewed to another length of paracord. Punched some tiny holes then use small zip ties to attach the two paracords together. A bonus is that u can use that paracord around the perimeter to hang anything vital you dont want to keep losing

 

[Batvette]

With the days getting colder, I have been pondering a heat source to avoid icicles hanging from my nose when waking up in the morning.

Not planning any suicide by propane or CO, but I have a number of high capacity tool batteries (and an e-bike battery) sitting in the garage asking for something to do.

So I bought a 60V to 12V converter (to get the battery voltage down to heater voltage) and a little car heater that convinced me with pictures of flames shooting out its grille and smiling people enjoying its warmth.

Electricity-wise, if the heater converts about 50W of electrical energy into heat, a 250Wh battery could last about 5 hours. The 600Wh bike battery about 12 hours. A little timer could turn it on around 2 am and off around 7... I know, 50W isn't much to turn a cold car into a toasty one, but the Ody is fairly well insulated, windows all covered with bubble-wrap and felt, so it may be enough to take off the chill.

Not put together yet... just an idea at the moment.

If thats really a 50w heater sounds like an exercise in frustration. Walmart sells a little 300-350 watt 110v ceramic heater I was running off a jackery 880. It was adequate but run time only about 90min. For a backup I have a cordless makita heat gun.

 

[Batvette]

Im assuming you have the rear heater turned up to max before you shut off the van? That fills the rear heater core with hot coolant which does provide warmth in the back for a couple of hours.