We were year round campers until we moved to east Idaho (we still camp year round, it just takes us longer to get far enough south to do so). While living in New Mexico, we relied heavily on our portable 130watt solar panel which we were able to point at the low sun angle. We also carried a small generator for back up. This is where Lifepo4 batteries really help in that they are energy dense and can be discharged well below 50% unlike AGM and flooded cell batteries. 

More time indoors.  Few hours for solar gain and low sun angle. 

Bring solar lights for outside around camp. 

I would never use a little buddy heater in a confined space.

Making coffee will warm up the rig. 

I really like a wall tent with a wood stove for cold weather but it is a lot of work. 

I would consider a diesel heater for a lot of cold weather camping. 

We can tell who speaks from experience on this thread. 

Park your rig in the sun. 

You can use insulating materials like the foil backed foam on the hatches and windows. 

Shore power allows you run electric heaters.  Much safer and quieter than the furnace or gas or diesel devices. 

The problem I found with the Little Buddy is that it is top-heavy. I tried it and ended up returning it because it kept tipping over, even with the plastic base. I got the Mr. Buddy heater, but it is way too much for the volume of the R-Pod. The Camco Olympian 3 is another alternative, albeit much more expensive than the Buddy heaters.

PEX cinch clamps are what was used in the RPod and also in the Grey Wolf. You could potentially try worm-drive clamps, but the PEX cinch clamps are probably better in the long term.

Maybe so but this is a great learning experience and will give you some real experience to make future camping decisions. When we had our 179, we were confident in camping all year round in the desert southwest because of the experiences we had in our hybrid Starcraft. 

I would suggest in addition to TT's suggestions, get a water carrier such as a 3 or 5 gallon jug with a spigot. That will save on the plastic of bottles. Be sure to sanitize it before filling and you will have safe drinking water for a much lower price than bottled water in the long run. You can find heated fill hoses. You could also wrap the drain pipes with heat tape and insulate, but the RPods are just not made for camping in freezing temperatures. RV antifreeze is an expensive way to flush, but it  can make possible a stay in frigid temperatures. We've done it. Be prepared to go through a lot of propane if you have to use it to keep warm. Best to heat to the low 60's and dress very warm. If you do use a propane heater such as a Mr. Buddy, be sure to provide for ventilation. Opening a window a crack and raising the vent fan's cover just a little can provide that ventilation. It helps both to avoid Carbon Monoxide poisoning and with moisture build-up. Electric heaters are better as they don't generate CO.

You can survive a cold snap that way. I would not want to try camping in an RPod in a location with extended sub-freezing temperatures though. Same with our Cherokee Grey Wolf. It also is not set up for 4-season camping.

If the campground has restrooms, use those.  Use bottled water for drinking. Be careful with any grey or black water. The waste water tanks can freeze too.  A little water might be okay, but at zub-zero none is better.  RPods aren't made for full use at that temp.  They are still fine for your own nice warm place to sleep.  If necessary to use the toilet, you can flush with RV antifreeze.

With full hookups, use your electric heater as much as possible.  You will have already paid for the electricity.

TT

Condensation will be your enemy. If you get damp, you will be miserable. So follow all of the advice on mitigating condensation and also, stay away from cotton. "Cotton kills" as they say in the outdoor sports world. It absorbs moisture and does not wick it away thus chilling you. While it may be tempting to have nice, thick, soft flannel sheets on the bed, they will be horrible if they absorb condensed moisture from the air. We use a good micro-fiber sheet set from Costco. They work great and are brushed for warmth.

Also, using any water in the lines or holding tanks is certainly out of the question in these conditions. 

Kudos to you for wanting to give it a go. Winter camping is something we really enjoy mainly because not many people do it and it is a completely different experience from camping in the warmer seasons.

That trip convinced me that if I really want to do winter travel, I need a winter-capable trailer. The RPod is really not a good choice for winter travel. To be sure, it is better than a tent, a pop-up with canvas, or a teardrop. The best one can say is that it is doable to winter camp in an RPod.

Good luck, and keep a sense of humor!