no subdued colours, no admin pocket (as far as I can tell) slip pockets don't look like they can fit a gi canteen and if by chance they do the ruck will be twice as deep as I want
I am being fussy I know but I've tried most styles out there...
You can get them in just black. It doesn't stand out much imo. I doubt there's a pack which will meet all of your requirements without making it yourself tbh . The normal daypacks which you find (like the osprey ones) will be the ones which come closest, but the packs made to be used as a daypack will not have an admin pouch, and the ones made for edc and city use, won't have the parts you want for daypack use (like bigger side pockets).
I don't understand your problem with the side pockets though. You say they are too small, but if they would fit your requirements, they would be much too deep? Sounds a bit like a contradiction. (I don't know how big they are, maybe you can see in a store. Better than looking at pictures and speculating )