Here is the follow up.
I bought two 10" resistive touch monitors from Carnetix.
Remember that there are a bunch of 10" brands to choose from and a couple 16" brands.
I went with the 10" because the 16s would look too big for my space.
The USB monitor functions more or less well. Almost all USB monitors use Displaylink drivers, and it seems OK.
The monitors came with well made but short USB to mini type B connectors. Cheap longer cables did not work correctly. I needed more length and did a search on Amazon to find some nice 6' cloth covered cables that work out well.
I am using a USB 3.0 hub from Pluggable, and it has worked out OK. Pluggable seems like a good operation with good tech support.
It turns out that the touch screen is not really usable. Windows 10 only will let the primary monitor be touchscreen. So if I use the 10" monitors' touch capability, it moves the cursor on my main 32" monitor like a mouspad.
Using the little monitor to keep Totalmix always available works, but with strings attached.
Every time you re-boot you need to put Totalmix back in the secondary monitor.
The Totalmix window kind of fits the screen but is REALLY small. If you are familiar with Totalmix, I can get the top two rows to show, but not the (unneeded) third row. If I had to do it again I would take a real hard look at the cheaper and bigger 16" products.
If I use my mouse to adjust the mix of lets say my guitar in Totalmix, I usually forget to move the mouse back to Sonar, so then my controls in Sonar don't work anymore until I go back and click on Sonar.
But overall it gets the job done of showing me Totalmix on a side screen while I work on Sonar or some other program.
It works for me, since I don't change settings much. If I had an active studio with more visitors, I would most likely install Makcie motorized faders with the Mackie Control, or something equivalent. But I would still use a second monitor to display Totalmix.