faux bourbon question

[midlife_rebel]

I am thinking of doing a faux bourbon run

Grain bill is 70% cracked corn
16% barley
14% wheat
running 2nd generations onward with 33% backset
and enough sugar to bring up the SG to 1.070 or so

I am trying to get similar to makers mark as my buddies like this style, but not wanting to go all-grain

Should I run like a sourmash by leaving the majority of the grains in for each ferment
or should I start with new grain each time?

What are the pros and cons of this? Thanks guys