Thanks for mentioning this. I'll be in this exact situation next week when I attempt to JS from ONT to ANC. I'm pretty lucky that I snagged the last seat (Pri 7) on the Maddog, but I'm not confident that I won't get bumped or that the Capt may not want 5 jumpseaters on his aircraft.

For anyone that finds themselves in this situation, the cab ride to LAX is an option, but instead I'll jump on the ONT-BFI flight (which leaves within 5 min of the ANC flight), take a $25 cab ride to SEA, and roll the dice with Alaska Airlines.

Personally, I would never leave any jumpseater behind if I had an available seat on my aircraft. If it's a little crowded, then so be it. I'm not leaving a commuter behind with limited options so that I can have a little more legroom, but that's just me.