Diesel Heater Inside Truck Camper?

Looking at getting a diesel heater like this one for my camper shell. I have a wedge popup like Topo Toppers/GFC etc. Everywhere I see, people are mounting their heaters outside the truck and connecting it to the truck via inlet/exhaust pipes. However, I've seen multiple sprinter van camper set ups with the diesel heater mounted inside the van (under the passenger seat).

Does anyone know how this could be done safely in a truck bed? I'm thinking... Just make sure the exhaust pipe goes through the window, or cut a circle in the shell and cover with a cap when not in use. The 6' Tacoma is only slightly smaller than a camper van (20 sq ft) so this seems like a no brainer to me.

 

Yep, just make sure your exhaust is routed outside and doesn't leak. Get a carbon monoxide detector to mount in the pop-up.

Having said that, I still mount mine outside.

As for the heater, look at the

$230 Hcalory TB2 HCALORY 12V Portable Diesel Heater, 2024 upgrade Toolbox 2 Diesel Air Heater 8KW 6L All-in-One Parking Heater with APP Control Work at Altitude Max 20000 ft for Car Trucks RV and camper

Hcalory TB2 Toolbox. The pump is quieter and it's a little more efficient (depending on whose review). There are other advantages, look at YouTube reviews.

ETA:
One more advantage to having the heater inside is the exhaust pipe radiates quite a lot of heat which is lost if the unit is outside. Still, I have chosen to put it outside.

One thing I wish was better with the Hcalory is the case is a cheap, relatively thin, plastic. If you decide to DIY you can choose a much better case.

 

Completely guessing but the one’s inside campers might high end, more like the Espar heaters in sailing yachts vs the cheap chinese diesel heaters most people have

 

a friend has his heater in his van but cut a hole in the floor to route the exhause out. its a vervor brand or something

 

I had that one (heater) and is pretty awkward to transport due to its shape.
I tried a cpl different cases, etc and gave up. Dragged it twice with me in trips after testing it and working fine at home, only to get errors, white smoke and being unable to make it work when needed, I'm still amazed I brought it back home and didn't throw it off a cliff in Moab or Mojave..

Bought this one: https://a.co/d/fnmukez
It fits perfectly in a tote, with all the pipes and hoses needed for it. It also has altitude self adjustment.
Uses about 2L/night and I hate cold. Still got a cpl errors a few times, nut i was able to restart it and turned on so I didn't sh8ver all night like with my previous one. In all honesty, I'm seeing it as pretty much disposable at this point, next time I get errors I'll try fixing it with the parts from my other one before getting a Webasto portable.

Now, I understand your question and post, but I'm seeing a permanent solution to a temporary problem.
How many times /year or cold season would you be using it?
It takes me 5 minutes to get it set up downwind from my truck and running, and im pretty anal about packing and unpacking, but, I only use it half a dozen times or so a year.

Unless you're living in your truck, I wouldn't drill holes in the truck bed or risk CO2 asphyxiation running it where I sleep, CO2 Detector or not. My cable is 8GA and 20 ft long from the battery, another 4ft from the heater. Exhaust pipes about 12 ft Total length and i can still smell diesel fumes inside the tent.
The heater runs hot enough with outdoor air to heat up our OZ Tent RV4 and the Awning room, so really, fuel savings would be minimal running it with warm air vs colder outdoor air.
When I travel alone, I can heat the cab of my 4Runner with just a 12V heater running off my secondary battery, your camper shell is about the same size if not smaller, so a dual battery set up might also be something to consider. Also, good sleeping bags.
If however you're planning on using it in -30 on regular basis, a Webasto or Espar, installed either in the engine bay or under the truck, running on gasoline from your tank, or diesel from an auxiliary tank might be an option to consider.
I would not use a Chinese diesel for a permanent install, look into Webasto or Espar, buy once cry once.

By the way.
The diesel heater inside the Sprinter van, is either a factory or dealer installed option, buddy of mine bought a Sprinter cargo van and it came with it.
It was cold as tits so I didn't looked at it to see if it's Webasto or Espar.

Also, when I lived in Europe 20 years ago, a lot of German vehicles had them(diesel heaters) even stationwagons and minivans.

 

Since i don't use it, I pulled out the 120v opening in the bed, mounted the heater on plywood platform and routed the exhaust pipe/muffler behind the suspension hangers so that it flows towards the trucks exhaust. muffler paste at a 90 degree joint, plenty of space around the radar and taillight wiring, the pipe gets to about 160~200F depending on the heater output, some bailing wire keeps the pipe centered in the hole.