Problem with 14 inch wheels is sourcing tires etc.
My plan was to basically build as per street fox but keeping the main frame/ batteries below the axle centers.
go with a 14-18 inch front track. Need to measure a scooter to determine wheel base. Why reinvent the wheel?
All the electric scooters I found using Google are one front wheel and two rear wheels and small wheels.
As for legality on the street, Portland actually has scooter rental outlets.