On boats and RV's you'd have to be plugged in to get long effective use. In both instances, I prefer propane tankless heaters. The only downside is they have to be vented but the smallest units are quite compact and very efficient. They can also be used as mini-boilers for hydronic heating if necessary.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13