Thanks for the pointer on where to look. The TLM612RCU is a convertible panel, but with a 100A Main Breaker Kit installed, it is nothing more than a 4/8. In order to install a second pump, a quad breaker would need to be used. It appears a TLM812RCU is the same physical size, but has more available spaces. Even with a 100A Main Breaker Kit, I wouldn't need to install a quad. Geez, this just keeps getting more and more expensive. Maybe I should just stick with a 4/8 and let the pump guy install 1/2" breakers if he needs the extra 2-pole. Or perhaps use the 6/12 and install a non-fused disconnect before the panel.

Thanks.