Yep your right steve VW trikes very common just chop of the back torsion assembly and all the running gear drops of weld on chassis and bike front and of you go. Not that simple but I have made loads and have photos if anyone is interested.As for back axle the new tuk tuk with daietsu engine rear axle should cope with it I have used reliant robin axles on bike trikes with no trouble.
There was a company called BOOM TRIKES based in Germany that used to ship VW based trike kits....anythong from a rolling frame to an engine or full kit to a finished model.
They also used to offer souped up engines that were absolutely crazy....
the look they had was 70's SoCal...cool if y like that sort of thing
I used to build them in the UK for disabled riders as they use hand controls, and the low slung saddle is perfect for getting off and on from a wheelchair.
Would recommend a VW based machine - the engines are usually pretty bombproof but there are some drawbacks....the sparkplug location for a start. They also tend to be a bit more substantial so not as light.....a consideration f you will be burning up any highways...
Yep your right sandman boom are still going but very expensive.Bestway build your own but get some weight on the front to keep it down then very stable on the road,Maybe could send out in kit form may avoid some tax if sent as parts.
I got both my bike and car licence in Pattaya and asked some general questions about what I could drive.
They were really vague about trucks ( I had a very large RV in the UK previously and towed a boat behind it )
I asked about Tuktuk and was told 'special licence, Bangkok '.
I'm not sure how much they were making up though or if they want an operators licence (Commercial ) !