you need to disconnect the fuel line, point it into an empty gas can and remove the vacuum line going into the back of the fuel petcock. Put another hose onto the vacuum port on the petcock and apply a vacuum to the hose with a vacuum gun or by sucking on the hose... but really, the tank might be a bit heavy, but it's not
that heavy when full.
ps- aren't you glad Heckel and Jeckel are up tonight?