If you use the wall itself...painted or raw, then the Panny can be set to automatically provide the size images you want for both Formats.
You can have the 106" 16:9 (52" x 92") and the 115" 2.35:1 (44" x 106") and not use any Borders at all.
It would seem your limiting factor is 52" of height. Shame that if true because with 60" x 106" @ 16:9 you'd have 122" diagonal.
Being able to maintain "Constant Width" will result in the biggest possible 2.35:1 image at 106" wide, and a truly epic sized 16:9 of the same width.
The hard facts are.....at 52" height, you will always have a image scaled taller in height in 16:9. If you have 106" width to work with, at least you can gain another 8" height @ 16:9
Something else.....even with Lens memory, Formatting bars in 2.35:1 still exist. The Panny's native Format is 16:9 so if you do NOT create a screen where the 16:9 image is smaller in height than the 2.35:1 image, you'll never have any issues there.
The Panny has a masking Feature...both Vertical and Horizontal, that works in conjunction with it's Lens Memory feature. This allows you to drastically reduce observable light spill in the unused portions of any Format. It's not absolute....but it is a usable feature.
The real key will be to place the Projector as close to the screen as possible, then use Low Lamp & Masking in tandem together, and with a High Contrast Gray painted wall. With no restraining Frame, your pretty much free to do what you want to.
Heady stuff, that.