It sounds as though you've put a lot of work into your touring rig and perhaps there are viable options out there for you to use. I don't know much about those options. I do know that once you start putting motors on bicycles you get into a myriad of laws which vary from one municipality to the next as to where they are legal to ride and where they aren't. Some laws deal with engine size and some deal with the speed of the bike. It can get confusing.

If you're going to pop a gasoline engine onto a bike frame I expect buying a Vespa Scooter might be much easier. If that really doesn't do it for you and you still want the option to pedal occasionally, maybe an old Moped would be a good way to go.

Let us know what you end up doing as it sounds like you have an interesting project in the works. We also love reading ride reports.