How about using "Control Mobile" and a handheld transceiver plus a mobile phone to co-ordinate. As an interim, obviously.
I don't know where you work but if it's at a UK airport you could always try using the apron control facilities of the airport operator as another option.
Have a look here also :
Welcome to ATC Global 10 - Air Traffic Management & Air Traffic Control Exhibition & Conference
There are generally 2 or 3 exhibitors with mock-ups at the show. Sorry, I don't have manufacturers names to hand but there always used to be several UK companies who manufactured mobile towers, mostly geared towards the military. I'm sure someone else on here can supply names though.
On the beach