Tyres come narrower than 559x42 - you can get 26x1.1 Schwalbe Durano that inflate to 110 psi. With less material than a 559x42 tyre they will be lighter and run at higher pressure.
Continental Gatorskins come in 26 x 1 1/8" and are popular with shops and riders.
Both of these tyres will fit on your rims with no problems (as will 42). As for the narrower width, plenty of road bikes win races and deal with city streets on less.
I run narrow Panaracer T-Serv's on one bike and bigger Schwalbe Marathons on another bike. On balance I think that over-doing the thinness results in too harsh a ride with no real difference in weight/acceleration, so maybe your plan to use Stan's NOTUBES might be either a) more hassle than it is worth or b) the only way to get comfort and light weight. You will need a bullet-proof tyre though...
I am not sure I would want a puncture with 'glued on' tyres, but that is not what you are asking. Ask at your LBS in the workshop for 'from the horses mouth' on the current deal on tubeless. Also check your rims make and model with 'Stan's' site.