Well I took the plunge on a Pocket Drive and also a Pocket Drive Pro since the deal was too good:
https://www.ebay.com/itm/144067471646
https://www.ebay.com/itm/133797952231
Now I can have one on each bike. I don't want anything too big but still usable in a pinch and well made and they seem to fit the bill.
Thanks again for the input everyone.
Edit: I don't know why both of my links are coming up with the standard Pocket Drive but if you search the sellers other items he has the Pro available too for $31 shipped, non Pro $20 shipped.