Captain Polo
We also have both.
1 The auxiliary hot-water heater (as it’s described in our specification sheet) is a feature of the V class vehicle, independent of the conversion. In terms of venting, it blows air into the rear cabin at floor level. The vent is positioned between the co-driver and driver seats. Assuming both vehicle and driver are in range of a cellular network connection (and the starter battery charge level is sufficient) it can be controlled using the Mercedes Me app either to switch it on ad hoc (for up to 50 minutes) or to set and activate timers (up to three set departure times per day). As discussed elsewhere there are limits on its usage. The remote is a Mercedes branded remote. The V class also supports other features such as using excess warm air from the engine when stopped and cold air but I would defer to my “co driver” who has studied the manual much more thoroughly than I and experimented.
2 The warm air auxiliary heater as it’s described is part of the conversion and is just that. It’s vent is located in the base of the co-drivers seat. It can be controlled (on off; timers; target temperature) from the Marco Polo control panel or via its remote if one is purchased