I'm looking to build a motorized bicycle with the following main goals.
-Very likely pull a bicycle trailer
-Economy budget
-Easy to accomplish conversion
-Back rest for my sometimes arthritic back, i.e. low rider/crank forward

I'm looking for a comfortable ride for fairly long hauls. Something like a low rider/semi recumbent is what I'm interested in.

I do have a 2cycle Craftsman (I think it's a)49cc still fully in tact which runs great.

I do not have the bicycle, reduction transmission, clutch, nor mounting stuff. I'm thinking the bike should be heavy duty.

I have considered a hybrid system with gas engine on the trailer hooked up to an electrical gen of some sort, maybe some batteries, and then send a power wire to the bike motor. But that seems extravagant, somewhat heavy and costly. But see, I also want to do some camping too, so I could use power for lights/laptop. But lets keep the motorized bike as cost and design efficient as possible.

Thanks in advance for whatever assistance.