A couple of you have asked about the heater we are using so I thought I could feature it and share it around the forums. It works great for us!
We were seeking something that used reasonable amounts of propane and put out optimal BTUs of heat. We also did not want a heater that had to sit on a flat surface and risk being tipped over by a dog. The Big Buddy is a great unit, but takes up valuable space. The old-style Coleman Catalytic was perfect, except it has to sit exactly level or it shuts off. Since space is limited in a VW van with 2 humans and 3 dogs we needed to find a heating solution.
The heater itself is a Camco Olympian Wave 3. It is widely available at RV websites, but nearly impossible to find on a shelf at a store. We had to order ours and wait! Prices range from $200 to $280 depending on shipping and seller. Here are some internet photos of the heater.
The unit does not come with everything you need to install it. You will also need a brass elbow fitting, a hose with a low pressure regulator and the feet if you want it to stand up. We had to get the brass fitting at a propane dealer. We used a BBQ hose and two extensions to get the length we needed. We skipped the feet for where we installed it.
The heater runs on any propane tank. We use the minion (spare propane tank) that is mounted on the outside of the van. It is on the passenger side, just behind the slider door.
The heater unit fits in the slider door window with a piece of wood underneath and a small strip of pipe insulation to help hold it in place.
The hoses attach to the elbow fitting 
and then dangle along the door as they reach to the propane tank in the back. 
As we open and close the door, the heater stays in the window. The hoses hang slack along across the door (yes, they may rub the paint, but we don’t care!) and the warmth keeps flowing!
Because of our installation we added a heat shield between the slider door track and the heater. If you look closely at the inside photo you can see the white piece of folded metal that is above the unit. It protects the van from the heat.
With this unit we can bring the inside temperature up to about 75 degrees at night! It also works great for drying socks and shoes! It is important to keep a window open. And we chose to purchase a CO2 monitor that we keep in a basket near our heads when we sleep.
The unit simply pops out of the window and goes in a storage bag when not in use. It cools quickly and we leave it assembled and ready for the next cold night. It does not take up much space and can install quickly. We love this solution for hour heating needs.
As always when working with propane and flames, please use caution and be sure you have checked all fitting for leaks. Ventilation is your friend and warmth is your reward.
This is just one way of keeping your vehicle warm. Do not try this at home. Do not attempt this without consulting a qualified professional heating/cooling installation expert. Do not work without safety glasses. Do not pour hot coffee in your lap. Etc.
Nice little unit!