If it's that high off the ground that's one heck of a plus. The floors are insulated, once you drill through the flooring simply push the bit through, don't continue to drill you don't want to drill through something you shouldn't. I use long flags and push them through to pull my wire up or down. Typical trailer thin walls so no fishing, unless you're mighty good. All blocks should be standard. If it's a prewired double wide there will be a box somewhere in the middle where the wires will be pulled to and you'd need to splice them together usually on one end or the other and well hidden.

Retired phone dude