MJ1966 You could technically use it as a dry rub, you would just have to do the calculations to convert what is designed as a pickle or injection to be used as a dry rub. Bacon has a limit on the ingoing nitrites to 200 ppm for dry rub and 120 for injection as charred bacon with way too high nitrites levels can be a carcinogen. Now, the 200ppm and 120 ppm limits mean you can char your bacon till it looks like charcoal without any health issues (though it’ll taste terrible!) so dont worry about that. How much does your belly weigh?
Yes, you can lay it flat, it will have some grooves in it from laying on a rack but that’s not too big of a deal.
If you do inject it then with the blue ribbon bacon cure it already has some sodium erythorbate in it so the only thing I would consider adding is Bacon Taste Booster. This is designed to give you the old world taste of dry rubbed bacon with injecting or tumbling. Now, if you do inject you should inject and then hold overnight in a solution that is 50% the strength of what you injected to allow the cure to equalize and disperse through the meat, better yet if you have a tumbler just toss it in there for 30 minutes after injecting.
Check out this for some more information on dry rubbing basics https://meatgistics.waltonsinc.com/topic/800/cured-whole-muscle-meat-104-bacon-basics