Flexor the Mighty!
18/100 Strength!
It makes things easier if you use group checks for the characters or groups of enemies who are trying to be stealthy and surprise.
So in a party with a couple heavy armor clad warriors and a rogue expert in stealth and a couple high dex light or no armor using people it all averages out.
I would think for things like group stealth you would roll off the worst stealth roll or something like that, the quiet guys don't muffle the racket a man makes walking around in plate armor.