I would convert the i4 to a nexus8 or afline8 or 11 for touring. This will go straight on , just swallow cost of a wheel build...
Its worth it.
Else go the dual drive route which needs a little problem solving skills but works really well. If you go dual drive cpq recommend s going for a d9 So yyou don't need mech hangers.

Going for a quality ihg means a lot less hasstle as you can keep chain standard , don't need a cassette etc.

It will seem expensive but save the money going for a cheaper i4 and put it towards the wheel build.

Try to get a later model with the better qr systems 2004 onwards??



There is a dual drive mezzo thread.

I have added a suspension telescopic seatpost that can be shared between my mezzos. That was very cheap and may be good at reducing mezzos harsh ride.