@ All, Thanks for the input, especially about the exhaust heat factor. Certainly wouldn't want a molten goo mass (or worse).
I had e-mailed Steven Harris about suggestions for a new muffler design, since this is NOT a quiet Honda and had hoped to vent it outside as well. But I've gotten no reply from him on the subject.
So - I'll throw it out to the folks in the community. Any ideas on how to reduce the noise signature some while not affecting exhaust flow too much? Just a note that this gen is over 20 years old so "Honda" parts may be non-existent.
Maybe a used 4 stroke dirt bike muffler/exhaust and a small piece of something like double wall fireplace chimney pipe going thru the plastic? Get a fabricator/muffler shop to curve a piece of 1" or so steel tubing so there's no "90's" like with a piece of galv pipe/fittings?
Or am I overthinking this?