No idea what you mean. (?)

Are you talking about filling your trailer TIRES with nitrogen, or filling the living space of your trailer with nitrogen?

If it's the latter, you can't have air leakage if there's no air inside the trailer to begin with. Also, I don't know why there would be any difference in heat loss from the trailer living space if it was filled with nitrogen. (?) It would seem to me that would be entirely dependant on the insulation (if any) you have in the walls of the trailer and the temperature difference across those walls. I don't see any reason for nitrogen to be any warmer than air under the same circumstances.

Probably a better idea would be to fill the living space of your trailer with helium and invite everyone over to have a Funny Voice party.