THe issue of using a 1oz 4-layer board (with logic) or a dedicated >1oz 2-layer board, is that the second option requires me to get about 20 boards worth (the cost per unit is actually much cheaper for what I get vs the first option). So if I go >1 oz, it costs me almost nothing to go straight to a 6oz board.
The most viable option it seems right now is to go with a 1oz 4-layer board and to solder wires between the power components almost on top of the leads covering the entire pad in a thick layer of solder between wire and lead. No power would actually be carried on the PCB, though the traces might try to act as a heatsink and it's possible they may get too hot (though there is the giant mass of wire and solder that is also heatsinking).
One external layer would be for logic components, the other would be for power components, and one internal layer would be ground. I don't know about the second internal layer, because as nice as it would be to have a logic power plane (all the motor currents are kept in wires), I found it a huge pain to route on a 2-sided board, and this logic circuit is going to be more complex than that circuit, so I kind of what to keep it logic routing...
I wasn't going going to make a star ground for the power grounds with wire, and the ground plane would be a ground for the logic, which would end up connecting to the power star ground (since that's where all the power enters). I was not planning on having any motor ground currents run on the ground plane.