In your zone, I agree not to plant Gold Rush, too late to ripen. Gurney sells a new apple variety created inthe midwest called Crunch A Bunch (silly name, I know) It is billed as early GoldRush. Per Gurney, it ripens in mid Sept. In your zone, may be late Sept or even early Oct.
Several of us planted it.
New apple varieties by Midwest Apple Improvement Association - #82 by Johnthecook.
I also like Hoople’s Antique Gold, it is russeted. Very good balanced apple ripen here (zone 6) in late Sept. My first Rubinette apples last year was not memorable because of so much rain intobthe fall.
I treat my apples with mininmal spraying of two sprays of Imminox for CAR and scab, then, I bag. Done.
Just curious, why you need two trees for each variety?
Another member here @Johnthecook, is a home orchardist who grows apples with a tall spindle method. Hope John can share his experience.