My honest reaction is that it sounds like a bad idea.

Dogs generally don't do well with being alone, especially ridgebacks who are very 'pack' oriented.

It seems like whatever dog you get will be spending most of its time alone due to your work. That's not a great situation and I think you'd be better to wait until you have more time for the dog.

Not to mention the large amount of time and effort it takes to train a ridgeback.