You know that it will be *very* tough to get >45min runtime on 1x123 with a boost converter that shall pump out some juice to the LuxIII? The NG converter by dat2zip is able to do about 750mA on 1x123 for approx. 45min, but the regulation isn't perfectly flat and this driver is in a very high efficiency range, so it will be difficult to find such in a cheap <100 product. If you are looking at anything more than 750mA you can forget it on 1xCR123.
Basically you are asking for a top notch high-tech light that should be cheap. Doesn't work.
The above light in this pic uses a McR-27 (even better than the Pelican 27mm reflector), has a 2-stage twisty tailcap and can be configured to your specifications. It is an Aleph1.
As an alternative ... if you happen to have a SF E1e light ... you can buy such an Aleph1 head and put it on there (Aleph lights are fully E-Series compatible) and use the Z57 clicky tailcap.
Alternatives to the Aleph1 head would be the McLux-PR and McLux-PR/T heads that followthe same path but do not sport the interchangeable LE (light engine) and lack some other features of the Aleph head. Those show up on B/S/T form time to time.
Here's a pic of a McLuxPR/T head in HA3 on SF E1e
And this is a McLux-PR head:
bernhard