How to solve the NEX7 lens dilemma?

Sounds like you are not afraid to invest in your camera tooling. Why not try out some of the options and EBay the ones that are not effective?

IMHO a small high-IQ 24-120 equivalent isn't going to happen (ie probably won't be far off the 18-200 in size, or will be consumer-grade, etc etc).

Perhaps you could keep the 18-55 for now and add a MF 135 + adapter (or for AF, use the LEA2 and a smallish Sony AF tele). I use a NikonE 100mm and its nice and compact even with the adapter... but spacewise I might as well carry the 18-200 instead of the 18-55+100 lenses.