Noah your not going to have any trouble with hardness in this type of cross and I do think you are on the right track. The "type" of cur dog you will use supplies the hardness with brains that you seek and the Dogo just give you a little more frame and weight without sacrificing anything else.
Keeping the litter and making your pics when they are at an age where you know what you have will produce results. I have worked with hard cur dogs for quite a while, when one or two can catch and hold grown horned cattle without getting killed then that is the right type of cur dog for a cross like this.
make them a 1/4 Stag and they might be perfect