Thanks for all of your responses as they are very helpful.
I think I am going to go with a 15 bar nuc for a variety of reasons. If the box has a front side entrance on one wall and a separate side wall front entrance on the other side wall and on the other end of the box could I keep two nucs in the same hive separated by a divider board? I would end up with two 7 bar nucs. Any issues with this set up?
As for me, this is not a nuc.
This is full blown hive (but a small hive with all the positive/negative features).
Mobility of the unit is an essential parameter - if it is to be called a nuc.
I want to be able to pickup and carry a nuc - alone - with bees and honey.
(which I have done exactly last night as I combined/rearranged the nucs for the winter - my back felt it - some nucs were heavy with the stores).
Afterwords, I loaded up those same empty nuc hives with empty frames, syrup feeders, some supplies and took them all home (transport box feature).
You can not do the same with your 15-bar hive.
At that rate - just make your hive bigger (say 18-20 bars) so you at least can keep two colonies in it comfortably (not overly tight).
And don't call it - a nuc.
Yesterday I consolidated two (4-frame and 5-frame) small units into a single 16-frame rig - side-by-side (but my full-size rigs is bigger than yours, I imagine).
That's 16 Dadant full size frame capacity (32 Lang mediums), I am talking about.