Sorry - it can not be done in Charleston... Not trying to be funny - unless you want to try the Cooper River - it is maybe 6 inch viz near Charleston/Mt Pleasant or up the river it is tidal dependent and has gators... There is nothing inshore other than sand and you need to go out 15+ miles to get 50 feet or more...
My sister lives there and I scoped it out - you need to dive from a boat... :-)
Which we did and it was fun - but finding 30 feet with viz is going to be hard pressed with out a boat.