danrogers, NiCad cells are capable of DRASTICALLY more current, on the order of 5 to 10 times more than the same capacity NiMH cell for pulse durations. In THEORY if you had a 80% efficient switch mode converter, you could do the same work with the pack described, that's with a lot of additional electronics components and maybe a 10-20% power sap of flight duration, not to mention the shock that causes to the chemistry in the pack (increased heat VERY bad), including all the additional weight of the components as the current used is quiet large so the components will be quiet heavy. Pulse draining a NiMh pack like that will increase pack failure rate by quiet a bit as well.
Everything about it says sure you could do that, but it'd be a bad idea. Existing system work too well.
The starter plug glow box drivers are for bucking 12V DC down to the current required for glow plug starting. A starter box is a 12 volt lead acid battery, it can handle the current draw, the NiMH pack's life would be halved.
Neat project, existing solutions fit the needs better.