Matt,

I'm not saying your blocking the hoses will hurt anything - because I really
don't know - it might.

What I did when this happened on an '85 I used to own was to get a length of
high temp hose and fasten it between the send and return hoses you speak of.
Creating a loop so the coolant could still flow. That "repair" is still in
place because a friend of mine now owns that van.

At least that way you could keep traveling with no worries and get a new
heater core at your convenience.

Good Luck.

--
Thanks,

Jeff
'90 Carat (Grover)
'86 (We call this one Parts)
'78 Bus (Melissa) Patty's Bus