Blowing air across surfaces that are in the conductive heat transfer part of heating an enclosed space will tend to increase the transfer rate. You can prove this by sitting in the center of a room where active heating is taking place. Now move to an exterior wall and either place hand on wall or stay in that area. You should notice temperature differences.
There are a few things working against you in an RV: the limited amount of wall and ceiling cavity space able to be insulated, the typical RV construction of not having a thermal break between interior paneling, wall framing, and exterior surface, the lack of insulated glass, and the inefficiency of typical RV furnaces and ducting. Anything you can do to raise efficiency of these is a definite winner. Some of these are nearly impossible or unlikely to be improved but there are a few practical things that can be done. Covering expanses of glass with an insulating material can prove very effective. Extruded foam board inserts placed in window openings at night is a good choice. Making sure that all ducting from the furnace is operational and not laying against a cold exterior surface is a good thing. Placing a fan behind any heating appliance to increase warm air flow and heat transfer from the appliance works well.
Possibly the best improvement in heating an RV through Winter is skirting the RV so that trapped air underneath is higher than ambient. You could even add heat lamps underneath to increase that trapped air temperature. Be careful of growing weeds and flora underneath as Winter progresses. I've camped in sub-zero f environments and skirting increases the comfort drastically.
