Hi,
First question, how many device do you want to connect at a moment?
I have two option for you now:
1/ The cheaper one, for $250 I can help setting up a usb-over-tcp server and client for connecting devices; also we have to use VPN server so that you can see which client is connecting. Then when you want to connect to client device(s), you just enter the client's IP address provided by the VPN server. If you don't want client to reconnect you just have to suspend their VPN account.
Problem is, it is not quite easy to use at client side. This support to concurrently connect 10 devices at once.
2/ I also have (resell) some kind of similar software which done exactly as you want, with simple comprehensive client which cost as much as the bid price for 10 devices connecting in.
Hire me. security code RD2D (ready to die?? :D)