I have seen a Goldwing some Wingnut stretched to ride 6 back to back...so, yeah a 75 foot CB would be unfeasible...what would a beast that long weigh?
Stretched Limos get really porky, the same would be true for a long wheelbase bike if the loads on a frame would make it difficult to keep from bending and dragging pavement... reinforcing it would add to the weight...spiral ensues and then there's the power to move the beast. If you have ever driven a vehicle with 26 foot box that complexity is tripled... Makes driving a semi with 52 foot trailer seem like childsplay.
But, thats idle musing on the technical complexities...