Simpler answer is to get a(nother) USB hub. I've got 6 ports on the machine, a 4-port hub inbuilt in the monitor, and an external 7-port powered hub. Not that all the ports are occupied, but the mouse gets to use one of the 6 on the machine.
Some devices are a bit fussy, but there's nothing tricky about sorting it.
Powered hubs are absurdly cheap on Ebay.