I was looking at who had the toughest schedule of the ranked teams as of April 17 and decided to base it on the record of the opponents as shown at the bottom of each school's site. W% calculated as follows W/total games.
4A School Opp W%
Lexington 66%
SV 62%
NW 60%
Aiken  57%
South Aiken 57%
West Ahsley 55%
Irmo 54%
Dorman 53%
South Pointe 52%
Wando 52%
Greenwood 51%
Summerville 49%
Ft. Dorchester 48%
Beaufort 48%
Rock Hill 42%

3A

3A School Opp W%
Bluffton 61%
Chapin 58%
Myrtle Beach 57%
Socastee 57%
Dreher 57%
BC 56%
Greenville 55%
HH 52%
Eastside 52%
NMB 52%
Wade Hampton - G 51%
Riverside 50%
Blythewood 49%
Wilson 49%
JL Mann 47%