what about gas generators?
can you set up your bike diesel locomotive style?
trains use the fuel to generate the electric to run the train the drive is electric so if you can take one of those portable camping generators.
http://cgi.ebay.com/RAMSOND-3200-W-INVERTER-PORTABLE-GASOLINE-GENERATOR-RV_W0QQitemZ150292726341QQihZ005QQcategoryZ106437QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
and then a power transformer to reduce the voltage to what ever your bike uses (if it a 48 volt system then you need 50 volts at 40 amps then convert the ac to dc to run the bike or charge the batteries.
another option is a small engine to run a car alternator wired to what ever your bike uses.
the thing is i am not sure what the law is looking at if it is the pollution,noise,fire safety,range to determine legality.