Having trouble with Building my small rocket heater for my campervan

Hello, Im new to this forum.
I'm from holland, and building a small rocket mass heater for my camper van

I used the plans on   https://batchrocket.eu/en/building


Heat riser diameter 70mm, 540mm long
Box dimensions 92mmwidthx165mmhigh 305mm long
Port dimensions 25mmx120mm
P Channel: 22mmx9mm
Primary air:30x30mm

These are all inside diameters.
Most of them are a bitt smaller than I planned before.
I made my burning chamber 90mm longer,  

When Its burning its rocketing a bit, But I think it could be way more.

When I add fuel theres a lot of white smoke, and I really need to open the door all the way.
When the fuel start to burn, I can close the door, theres some rocketing, but I can also see a littlebit of black smoke.

So I think I'm almost there.

Could have some tips, how to solve this problem.

I made a video, some pics, And I  add a drawning with some measerments.




Pictures:

https://ibb.co/Y8s6QMy
https://ibb.co/zb0cCsH
https://ibb.co/bzP9fGg
https://ibb.co/SXbc5Q0
https://ibb.co/Hn0hBwc
https://ibb.co/w0sJWWW
https://ibb.co/dBTDJBg
https://ibb.co/7k7XbRD

camper van--yeah, great idea. portable rocket mass heater--awesome idea

Typically, a small stove is a lot more finicky to run than a larger one.
I believe its mainly due to the fact that it just doesn't have enough open space where the draft is not being affected by friction posed on the uprising gasses known as the boundary layer.
Many people have in fact chosen 6" to be the smallest stove that will run reliably in almost all circumstances.
I've heard of several people having pretty good luck with a 4" stove but they also don't run it that much, only to get a chill out of the building kind of thing.
Although its certainly not impossible to keep your little stove, you probably will continue to have issues that you'll never overcome.

Oh yeah,   BIG welcome to the rocket forums!