In my experience the rear handle works great in it's stock (I
think?) horizontal orientation.  The way that I use it is to slide the door
into the almost closed position and then grab the rear handle and gently
pull the door inwards (towards the fridge) to close it.  This way you are
not slamming the door which is nice when camping with others etc.  It is
very hard to ease the door closed from the inside with the front handle
only.

Like others have said, if you can ease the door closed by pulling it in then
you need to lube/clean the tracks etc.  Don't overlook the roller that runs
in the track at the bottom of the door (at least on the early models).  I
found that removing that roller and cleaning/greasing it made a big
difference on my sliding door.  You may need to remove the door to pop the
roller off which is an easy thing to do.  I like to keep 5 gallon buckets or
such around for props so that I don't have to lower the door all the way to
the ground immediately as an end is disconnected from the van.

Jonathan Poole
'82 AC Westy