Regarding going lower than 30t up front - the 30t-27t combo is plenty low enough for my workout 30-40 mile rides with at most one bad climb. Something longer with more climbing I'd put on an 11-36 in a heartbeat (with properly sized chain) and be pleased to survive, karma aside. There are two organized rides that are too tough for us on the tandem, even the 100K version, and I really want to ride these on my single which is where the 36t cog would come in.

As for tinkering, I don't now which is more/less expensive, N+1 or tinkering on one's only ride. When I get my hands back on my old Miyata I'll try to tinker it back to near original.