Anyone with experience with Kei Trucks?

[Marklovski]

AFAIK, all of those kei trucks are 660cc. So I assume a 4cylinder isn't a thing unless you go with something larger? I didn't know kei truck campers were a thing. I saw a video where a couple guys made their own campers and did what I think you're talking about. It's somewhere on youtube.
I was tossing around the same idea. I briefly looked into importing one but it sounds like a hassle and a gamble.

So the Kei Van models have the same chassis as they kei truck. The Mitsubishi Minicab and Bravo van have a 4cylinder option, I think the Bravo van is more common though.

Japan has a ton of companies that build campers out of kei trucks: https://youtu.be/tAOttYejUgc, https://youtu.be/w2MFziDLDLM

The Japanese also have a scene for custom campers: https://youtu.be/PCchHwJj00Q

I just have trouble finding parts, the websites I've seen either don't have them or aren't specific on the compatibility.

the parts supply chain would be my concern. For example, I can't find any parts for a Husqvarna made riding mower, sold by Sears in North America, not that long ago.

And you're hoping to keep a 25+ year old foreign made never imported vehicle on the road? GL with that.

While they are old....they are low miles. Thats why I'm considering it. People here want $20k for their 20 year old truck with 200k miles. I would be more comfortable with a kei truck with 30-50k miles. I also think it would be easy to get views on youtube if I decided to go that route. I would definitely bed line the under body and paint over everything to make sure nothing rusts. Maybe I should find a Suzuki Aero powertrain and swap it....