Ohbse,
A few things, 17" wheels you feel potholes, 19" you feel them less.. I am interested in doing a mid-mount so a simple change of gearing fixes any cruise speed issues with motors in minutes. Bike shops everywhere. Might just put a few front drive gears under the seat! Pull over for a pit stop, swap the front gear, maybe make the rear wheel with some fore-rear range on the bolt. No chain mods for a gear swap this way.
I had a Honda Cub 50 in Cambodia for a daily driver for about 8-9 months, and it was too small. Check my profile for a recent post about ebikes in Viet Nam. 500 USD goes a long way. But I am average western sized, and usually tallest in a crowd here. These bikes do not fit me!
I also had a 90 cc Suzuki scooter in Nha Trang, Vietnam, fun city BTW (great place to retire), for about 2 years, a bit small for longer rides. Knees near chin = no good.
And I had a Yamaha 420 cc dirt bike in Cambodia which was light, nimble, and had scary good power. Front end up in any gear with the a twist of the wrist. But my collection of scars is hopefully complete, and while Doctors can be nice people, I am not eager to meet more on short notice! Things are a little more black and white here, as in no cash = no enter the hospital. "YOU GO NOW!" or DEE DyIE (rising tone on the eye part at the end), loosely translates as "get the f away before we have to kill you.." Still medical care is cheap, had a mole on my shoulder start scabbing up last week, went to the dermatology hospital, 5 USD for the consultation, about 30 minutes. Paid 25 USD for the stain test biopsy thing, had to wait 30 minutes before seeing the doc, and test,explanation was another 15 minutes. Results the next day by email. No cancer, but burning it off with a CO2 laser was $20 if needed. Took about 2 hours total! 30 minutes each way by bus for about 30 cents each way.
As for licenses, not sure what you mean, but I will address both possibilities:
1) No drivers license for less than 175 cc. None, no restrictions. Any age, anybody, foreigner or not, no license..
2) License plates - those cost about 10 USD when you buy the bike. They stay on for the life of the bike, no renewals, ever. This might be a slight theft deterrent. Ebikes have no plates.
No drunk driving laws either! so just go slow, and no problems. Hit anything as a foreigner, IT IS YOUR FAULT. Even being hit from behind. "If you were not in our country, there would be no accident. YOUR FAULT!"
And theft is always a concern. Everybody parks indoors. I can touch my under-desk beer fridge, my moto, and my TV from my favorite chair. Cars also go inside the house.. There is usually a ramp in the middle of the front steps of each house. Sometimes temporary wood or metal ramps are put in place, then retrieved after use, but many houses have a 6 inch wide concrete strip up the middle of the stairs.. Dogs and cats, go INSIDE THE HOUSE. Everything goes in the house.. Even plants are brought inside the house every night. All that said, I have never had anything stolen in over 4 years. Not sure what the penalties are here, but China when I was there 7-12 years ago, had the death penalty for about 600 USD of value. Total value after they search your house. Any serial numbers found reported stolen count toward the limit. The whole court case, beginning to END, usually drags on a few days.....
And a Honda Wave with disc brakes, used 2-3 years, is only $600. Toss the motor, stretch the frame and swing-arm and VOILA, ebike action here we come. Or just buy the front-end as parts, and have a frame welded, build/buy/steal a swing-arm, get a rear wheel with disc brake, and have no extra parts. Kind of like we are discussing here!
I teach English, about 20-25 USD per hour tax free, so not a super huge expense for batteries and motor. Call it $2000 total, still much less than a cheap scooter back in the USA.
Wanting something upgrade-able, which the ebikes are not good for. With the smaller motorcycles/scooter, you get bigger everything, better brakes, and room to add batteries for speed or range. Better shocks, etc.