Re-reading this thread (Did not comment the first time) Many dealers do not have sewer connections for an RV.. So that is understandable.. My own dealer did not have that ability.. however there is very little that can go wrong with the sewage system, it is powered by gravity and if that ever fails.. You are going to know it pronto. (you will drift off into space and explode). The only possible issue is a valve that is stuck shut.. I'm sure their techs can check that and perhaps even demonstate for you.
POWER.. They should be able to provide 15 amps. this is enough to run lights, Television, and one at a time the following
Microwave
Water heater
Air Conditioner
But you may need to wait six hours before doing that depending on the converter and battery state of charge (My converter is a "Big Ticket" if the batteries are dead, Tiny load if they are full up.)
Of course.. you did mention it's a motor home (Make and model) I believe.. No need to hook to shore power.. Has Onan Power.