i have a 73' w/ similar problems. Basically you are in a big tin box w/
lets out heat as quickly as it is generated. Similarly, sending heat all
the way uo that tube to the front of the car makes it quite prone to
cooling off. Assuming everything is airtigh and well isulated I would
suggest that to make driving more comfortable, make some sort of partion
between the front cab and the rear sleeping area. That way you don't have
as much space to heat up. Make a see through window in your partiotion by
using that plastic you put on the inside of your windows at home, and
shrink it to taughtness with a hairdryer. For heating the sleeping area, I
would suggest looking at aftermarket aux. heaters. I beleive Joel Walker
posted something about this a few days ago

>I have a 77 campmobile.  Its lots of fun as long as the temp is over 40.
>Anybody got some suggestions on how to heat this thing.  Most of the
>heater parts are new.
>george McCabe