Piano recording in living room, ceiling treatment options

I'm beginning to plan portable treatment procurement. My room is 13'x22'x8' (LxWxH) Hardwood floor, plaster ceiling, all opposing walls are parallel. This is a high finish living room, and I am NOT - I repeat NOT - allowed to drill into or modify any walls or the ceiling. The domestic engineer has made that point loud and clear. The primary (audio) purpose is to record piano, also to record drums on occasion. I am already planning to construct a number (yet to be determined) of skyline style diffusers and absorption panels mounted to portable stands which can be placed around the walls. I also plan to build portable 4" thick absorption panels to straddle all the wall-wall and floor-wall corners for bass absorption. My question is with regards to the ceiling. I understand that diffusion is not effective in the near field (an 8' ceiling falls into this category I suspect), and so is not really a good option here. Is this correct? I've come up with the following design to combat ceiling to floor flutter echo: Four Manfrotto Autopoles suspending 4" OC703 panels in a custom frame with a 4" air gap. I'm debating how many of these to buy/build, and I'm debating where they will be best placed when built. For the most part, I want to record jazz, and so I'd like to be able to record with a main pair that is 10' or more from the piano, as well as use spot mics and balance to taste. Will localized ceiling absorption placed directly over an instrument help significantly with flutter echo picked up by a main pair (placed, say, 10' away) in addition to flutter echo picked up by spot mics? Or do you need to cover large ceiling areas to help with flutter echo recorded by distant microphones? Or is the most effective/simplest method to place localized absorption over the main pair? Most importantly, am I heading in the right general direction with my treatment plan? Thanks, Dave