How to make rolls airier and crustier?

I'm working on a bread roll recipe that's 66% water (it's wet, but I'm still able to shape into rolls), 4% powdered skim milk, 1.8% ADY, 1.6% salt, 10% sugar, and 8% shortening. I divide the rolls into 30 grams per roll. I spray the buns and put in extra steam in the oven when I bake them. I also start the first couple of minutes of baking at the highest oven temperature, then drop it to about ~300F/150C for a total baking time of about 15 minutes.

It's a very basic dough recipe. When baked, the rolls come out slightly sweet, very soft, and moist. It's a decent bread roll.

However, I would like the crumb to be a bit airier and slightly drier. And I want the crust to be slightly thicker and flakier (but not as thick and flaky as a French baguette).

What adjustments can I make to my formula to achieve the crumb and crust texture that I am looking for? I'm thinking that less sugar and possibly less shortening might help? Would those changes help me?

Also, besides changing my formula, is there anything else I can do to help achieve my goals?

UPDATE: should I drop my shortening to 3% (see: https://en.wikipedia.org/wiki/Bread#Fats_or_shortenings)?