Dont forget that there are two different systems for the tip tanks. One where selecting tips transfers fuel from the tips to the mains, thats why one has to wait until there is space in the mains. the other system ( as fitted to the -21 model ) feeds the engine directly from the tip and closes off the main.

the under wing tanks were gone before I flew them although they would have looked good installed and painted green with a yellow tip.
On the -27 the tip tanks only transfer to the mains, they don't feed direct to the engine.

Take Off check lists ?
 

Do the "standard pre flight checklists" include checking fuel switches are set to Main Tanks ?
Plus surely as soon as the first engine stopped (and even as it was spluttering) the first thing would be to change to Reserve tanks ?
(then the Pilot would immediately have found he was already on Reserve tanks, and switched back to main & restarted the engine)