Minimum Weight and Adding Fuel

[Thomas Harrington <tomh@lvcm.com>]

I was just curious how minimum weight is measured with regards to adding
fuel.  I know in stock class that you can add fuel between every run if
you wish, but what about classes with a minimum weight, like modified or
prepared?  Is there anything to prevent someone from running with empty
tanks just to add fuel before impound to make weight?  Or perhaps taking
2 runs on empty tanks and adding fuel to make weight on their third run?

Just kind of curious...

-Tom