[gurps] A rule or house rule for 'monotracks'

[Onno Meyer]

A friend found pics of an interesting model vehicle on the net. It
was fictional, I presume, but I don't know even that much ...

The vehicle looked roughly like a motorbike, but with one (flexible) 
track connecting the two 'road wheels'. It was possible to turn the
front wheel a little and hence to steer a little, but in the real 
world it would be a constant struggle to avoid slipping a track. 

His question was how I would GURPSify it. I checked the rules in 
Vehicles, and they say clearly that a tracked vehicle has two or 
four tracks, no other number. Unless there is some optional rule 
I missed, that means I need a house rule. Some ideas:

* Just go ahead with a tracks subassembly and a tracked drivetrain.
* A motorcycle seat is required, since the driver has to balance the
  vehicle just like a motorbike. The weight must be something he can
  balance, too. 
* Make it TL8+ and require smarttracks (possibly without any of the 
  usual benefits).
* Possibly make it articulated to represent the headaches of turning
  a track. 
* Speed/Accel/Ground Pressure as for tracks; gMR and gSR take the 
  worse of 'tracked' and 'two-wheeled'. 

More suggestions?