Bill, usually doing a ladder load work up makes things far easier than more difficult. I've been finding that most of the time a reasonably good hunting load can be established with 10-12 rounds fired.
But then again, most of the rifles I use are bolt actions and most are bedded and not nearly as
"sensitive" as what this #1 appears to be!
Also, I dont' have much experience with the #1's and I'm exceeding the max powder charges listed and even though the RUger #1 is much stronger than a SMLE, I still like to go slow and safe when working up loads in what is to me, "uncharted" territory.
Plus, it's interesting....
That being said, the reality is that I will likely first shoot a blacktail deer and a black bear with this rifle, and both will probably be about 25 yards away, so your method does have merit.
I loosened off the forend screw a bit, going to see what the local shop has for ammo, see how that works.