Tracy,
I didn't see anyone comment on your trip report, so I have a couple of thoughts having been the happy recipient of a similar on-site debug visit a few years back.

Have you thought of offering this as a paid service? I know you're time is stretched between too many things already, but maybe you could turn lemons into lemonade here. I'd bet that you spend more hours trying to debug these problems remotely than you do actually flying there and eyeballing them. I know you did with mine. I also know that I'd have willingly paid for your time and gas to run your experienced eye over my installation before I bet my life on it.

Is it possible that adding a few such (fee based) trips would reduce your support workload, increase your net revenue, improve client relations, AND give you a excuse to aviate, all at the same time?

John
Turbo rotary Cozy IV
(just short of 100 hours)