i think you can get away with just 2, a big 3dap and a giga ruck, if you fill them less just sinch them down.
I'd also add an EDC pack that's separate for the fact that it's easier to manage but otherwise you can just do 2.
for example I got a mystery ranch 6500 but you can compress and close the sleeping bag compartment and it becomes a SATL basically.
but since I'm a pack consoomer I was thinking about buying a mid ruck, i just cant decide which, I like the satl, but the ones i find are old gen and have the small hip belt, that concerns me as it seems it may be shit at load bearing, unless you buy a new gen from varuste or some other retailer if it even exists but i was trying to go used so to save some money (I know sellers that hav good condition used stuff), otherwise there's the beartooth 80 which is a very good general purpose ruck and has a cool design with the 270 zipper, but it's expensive too so I might wait a bit before buying. I also like the kifaru 357 mag or the blackjack 50.

has anyone tried the old gen satl? is the small belt really a problem?
btw my 6500 is old gen and has the internal frame instead of the external pike the new gen, is there much of a difference?