You can also, Christopher, use 350 to 365 grain bullets with the same charge of powder as your 500 grain load. They should regulate (called the 3/4 effect), but may print a bit higher on the target. Once you begin to reload, IMR 4831 should give you enough loading density so you do not need a filler.
Yes, try the first two shots off sticks and then move to the bench. I used a Paste recoil shield when working up a load for my 500/450 which is about the same recoil as your .470 but that old rifle was a half pound heavier.
Practice drill included two rifles: 500/450 and a double in 350 Rigby No. 2 (you can use a bolt in 30-06 or what have you). Fired big bore standing, offhand at 50 yards, just four shots. Put the big bore down and fired ten, standing offhand at 100 yards with the smaller bore. Then back to the big bore for another four. Started with just 12 big bore, ending with smaller bore. Fools yourself and dodges creating a flinch. Also good practice shooting off hand, and very good for learning how to reload the big bore quickly (then break it open as you use the smaller bore).
Best of the Season,
Tim