Space requirements for four rabbits?

I'm struggling to find any info on this! I know the minimum requirements for a trio are 48 square ft ( feel free to correct me if i'm wrong!), but what would be the minimum for 4 buns living together? Would 52 square ft of permanent housing consisting of a shed/ aviary, with daily supervised time in the garden be adequate? Or would this fall short?

Long term plans ( within the year ) are to extend the aviary by an additional 18sq feet, but i haven't broken this to my husband yet!

what size/breed are your rabbits, or if they are babies, what size will they be?

Two dwarf lops and one lionhead cross, with possibly a second lionhead cross. X

I also wonder this - hopefully when I get a place of my own I will be in a position to built a large shed/aviary combo and bond my four into a quad!

Mind you I've already decided they are having much more room than they all need

My quad had a 6x8ft shed with their own garden every day which was about 6ft wide x 24ft long.
I know they don't NEED that space however.
I think maybe a 6x4 shed with a big enclosure during the day should be okay?