> I'm not sure which is "in" and which is "out"

Where they come through the "firewall" the lower one
is "in" and the upper one is "out".

In an emergency, such as this, just disconnect each
hose from the heater and fold it back.  You can hold
the fold with a clamp, a wiretie, some string, some
duct tape--or have some one hold them while you drive.

Folding back is standard OP at the end of irrigation hose.
Adapt to Vanagons....

Richard