I don't think this is what you're asking, but this might help (or not). I BIAB exclusively in a basic pot/kettle. System losses are something that took me a bit to dial in, but once I got there, I can pretty much guarantee how much beer I will put in the keg. This is a bit rudimentary, but you'll get the idea...
If I wanted to make your above beer, this is how I would calculate my full mash volume:
Grain weight (lbs) - 8.375
Mash Volume = Goal + all losses
Goal = 2.5gallons into keg
+ Grain absorption (.11gal/lb) = .92125gal
+ Boil Off (.67gal/hr) = .67gal
+ Kettle Loss (fixed) = .625gal
+ Fermenter Loss (fixed) = .5gal
Full Mash Volume = 5.22 gallons
The grain absorption and boil off are what I have found to be consistent numbers on my system, though absorption really comes down to how long and how hard you want to squeeze the bag. I squeeze just enough to hit my pre-boil volume and then quit. Kettle losses are a bit fungible as well depending on how much trub you leave behind. Some dump their entire kettle, trub and all (0 kettle loss). Others will leave different amounts behind. (There is also a "shrinkage loss" that is a bit of a unicorn to me, where your post boil volume at 200°+ will be somewhat less once cooled to yeast pitch temperatures. I have no idea what this number is so I just kind of lump this into "Kettle Loss".) And, of course, Fermenter loss is how much gunk gets left behind at packaging. I rarely need to leave behind a full 1/2 gallon, but I play it safe.
So, if I were brewing your beer, I would be using an 8-gallon kettle. Of course, you can mash thicker and sparge to get to your pre-boil volume. (My pre-boil volume is always 4.3 gallons, assuming I want 2.5 gallons in the keg). You can also just accept less than 2.5 gallons finished beer as well.
I spent many brew sessions trying to increase efficiency and limiting system losses. I learned a lot of things, but it felt like I was just chasing my tail. The loss numbers above may look bad (or good) to another brewer, but they are stone cold predictable for me. And in the end, that's all I'm looking for. YMMV.