I am building a buddy seat pretty much from scratch and trying to figure out the seat dimensions. SEE PIC BELOW: I have the one side piece as a starting point but need to know the width and depth of the seat in order to add the full framework. IE how far out from the bulkhead does the seat protrude and also the width from the bus sidewall to the outside edge of the seat? Any help with measurements and hints on how to secure the seat in the bus would be gratefully received. Cheers C