While I don't really know about the rust risk etc. it seems like it
would make sense to redirect that water to a place that you can more
easily monitor.  When I purchased my van it had only been used
occasionally in the decade preceding my purchase and had been parked
nose up (slightly of course) for the duration of those years.  There
was considerable moss/slime/etc. growth on the paint inside of the
intake.  I had to remove the grill to clean it all off.

Also, I don't know if any of you have this problem but on my '82 if I
am parked with my nose slightly uphill and a nice and quiet, light
rain comes along I get this really obnoxious tapping sound that comes
from the water dripping in through the passenger side air intake vent.
 I have performed multiple middle of the night moves because of this. 
Just when I forget I park rear down and a light rain comes.....  I
just need to fix this..

Jonathan Poole
'82 westy