Follow up for anyone actually considering this step:
So I did this procedure yesterday. It was no trouble at all, I made an open faced aluminum foil funnel to lead from the oil filter housing to an opening to the catch pan under the bike.
The dirty oil could be seen pouring out at idle into the pan, very manageable. I let it run a little past the point the oil started to come clean.
Looks like it cost me about a half quart of new oil.
Installed the new filter and all was well. I actually made more mess from my first use of the awkward HD rubber tube drain system than with the improvised enema system.
Reality check: not surprisingly,I noticed there was a bit of sludge at the bottom of the oil tank, so no doubt there is also some @ the bottom of the case, some of which will mingle with the pretty pristine new oil.
Oh well, at least I got more of the old oil out than usual.
I won't bother doing it again, but it was somewhat gratifying as a first oil change on a new old bike