Under the Sink

There are many areas where this is true, but the locations differ depending on model - and model year.  For instance, on my early 171 they divided up the front-left under-seat storage between the converter (lid screwed closed) and open storage (lid hinged).  More recent model years left it all inaccessible unless you modify it yourself.  Even on my model year I've found several areas where you can create more storage by removing panels (under the fridge, and under the bed).  Some areas you must be careful due to wiring or piping, as you thought.

We have the 177. I removed both panels and the floor you see (in the 177) in front of the panels goes all the way to the outside wall. There is an immense amount of room back there. I put a small plastic bowl over the electrical relay.. to protect it and cut small access holes for the wires and to allow for air movement over the relay. We also put an outside shower there and still have tons of room for storage under the sink.   Any wires etc. there just move them off to the side and tie them together.   Good luck.