Previously I mentioned an old article by Mike Marshall about how he would structure a rotation and bullpen that I could not find.
I finally found it. Why it didn't come up in my prior searches is beyond me, but this is definitely the article I read 10-11 years ago on how Marshall would construct a pitching rotation.
It mostly confirms what I remembered, but it turns out his pitching staff would only have 8-9 guys, and he would use the rotation pitchers more than I thought. They would in fact be his middle relievers, and he'd even go as far as to send them one time through an entire lineup if he had to. His bullpen would only have three men: Two alternating closers who worked the 9th inning on alternating games, and one mop up guy to get the team through the 6th if the starter got shelled.