I have trimmed down weedy lawns to a height of 1/2 inch and no more than 1 inch. The existing grasses were not dense..by no means, and then warm season sod laid on top. Fertilizers were applied before and lime. The warm season sod did fine with ample periodic watering. The plot was level to begin with, so don't get this mixed up with bumpy novice sodding practices. The sod will settle in and will flatten out in time but not to an extent of the existing grade.
Riggle, I am confused about what you are proving unless you are trying to prove success with mediocre cost involvements.
I have had numerous issues with cost factors from certain clients that want to skip the grading, complete kill, and soil prep steps to save money to the bottom line. Even after the sod is rolled in the outcome is somewhat iffy. In a pinch, if tilling, rolling, and other soil prep work isn't in the budget of the customer, then you can do the top sod method and have success.............don't know about sodded fescues and bluegrasses.
One year, a local supplier sold fes-blue sod and made a killing on locals.......but the reality wasn't very prosperous. Let's just say that he didn't hang around long and if he did, his credibility would be bolstered with ridicule.