I did consider this some time ago, but ended up doing the full FI/CPL in my spare time.
The thought was that I could do some of the more interesting stuff like tailwheel conversions, as well as club currency checks and 2 yearly instructor trips.
I should imagine that many clubs would welcome being able to off-load some of this, especially at weekends. I'd be interested to find out how you get on once you've got it.
I find the CRI type instruction to be as enjoyable and rewarding as the ab-initio stuff. It often gives you the chance to fly with, and learn from, some very experienced pilots.