There are plenty of wires that already go from the front/cab to the back of the RV. You should be able to route your wires with them. On my class C, there's a big bundle that goes more or less under the driver's door sill and then to the house part of the RV in the corner of the cab behind the driver's seat.
Not infrequently the brake light wires etc. are run along the frame rails, I think, and this would be one practical way of routing your video cable. It might be a good idea to put it in some split loom tubing or similar for protection from the elements if you do this. Alternately, you may be able to route it with the furnace or air conditioner ducts or interior plumbing/wiring if some of that is reasonably accessible. It really depends on the specific layout and construction of your RV what is or isn't easily feasible.