Generally all of these water lines and power wires can be accessed through closets, benchseats, etc. On our UHaul
, you can remove the benchseat cover and have access to almost everything. The closet also unscrews, as does the sink cabinet in the bathroom. There is nothing that I haven't been able to reach, but sometimes it takes a bit of flexibility! Everything is above the floor and internal except for the drain outlets.
OK, that's for the UHaul
. Hopefully others will chime in about Bigfoots and other trailers.