[Stephen of REX]

The KOP CIMple gearboxes should have spaces for your additional CIMs.

Dropping the center wheel or using omnis on the outside is a bit of a tradeoff. Using omnis will keep your robot more stable and make it rock less, but aren't as good for pushing power. Dropping the center wheel will introduce some rocking, which could be detrimental trying to reach the high goals. However, you will gain more pushing power.

I would recommend sticking with the KOP chassis, but that's just my opinion. Alternate drivetrains can be lighter, but usually take more time to make and are more complicated.