Placing transformers in a series

Just connect the common from the LW to the out side rail and the hot side to the fixed voltage plug on the switches. 

You're correct. As long as it's connected to common, it makes no difference where you physically connect it. 

You're technically not putting the transformers in series. You're putting them in parallel, by tying their common busses together, so that you have in essence created an additional output from your system.  It's sort of like getting 5 outputs from your ZW. Just be sure that the two transformers are in phase, and you will be OK.

Look in the archives for both the theory and practice of transformer phasing. There have been many threads about that subject.

Parallel, and IN PHASE, is what you want typically for your proposal. 

For layouts with heavy current drains and marginal wiring(especially on the common return bus), there are advantages of wiring accessory transformers out of phase, but that is an unnecessary complexity for most.

Hi,

   I connected the commons for both transformers and it is working well.  Thank you all for your input, I will look into the phasing aspect as it may help me down the road.

     Kevin

Click on the IN PHASE link above for an excellent tutorial.