That's pretty much how it works, Mark.
There ARE limits. The film, for one thing. TMY & TX are great for this. TXP, not so good.
Neopan 400, not good, for different reasons. FP4, great.
It will probably be sufficient to make 3 all purpose negatives. My 'Sangre de Christo' negative would have normal contrast from IV to VI,
and would run out from there. You've got the idea perfectly, as well as live in a place where it would be handy.
Sit down with a pencil and paper and draw the 'ideal' curve for your afternoon portrait. You might very well be able to make it.
Using LPD or 130 instead of Dektol gives your paper greater range to hold these tones, and split filtering will be easy if you need to hold a longer scale.