I'm having trouble understanding your plan, If you are mocking it up, post a pic when done. My thought is that you are thinking of locating the dog's spot over what would typically be the motor well. The absolute last place I'd want a dog is on top of the motor well and in front of the motor, but maybe I'm not understanding your plan. A dog anywhere near the rigging would be a nightmare when they launch themselves in our out of place, the wiring and fuel lines aren't exactly fragile, but dogs aren't exactly gentle. Not that dogs aren't always in the way already, but you are training them that their place is to be right in the way, their safe spot is going to be to jump right up on the tiller whenever they think it is or want it to be time to hunt.
There are some of the larger boat blind boats that have full width wells with dog platforms. Look at the Bankes larger ones, maybe the duckwaters. These are only really feasible on a really beamy boat as you are having a hard time fitting the dog somewhere. Boats with a stern dog platform are just a totally different class of boat in terms of size.
It seems like you are committing to a tall blind 100% and while a good tall blind works well for divers, you will be limited for puddle ducks unless up against some sort of significant cover.
I drawed up this idea for you:
View attachment 63979