sv_pure 1, but force everything on the whitelist to comply to the crc_check. This will be a bitch for server resources (recalculates on each new map).
PunkBuster employs a similar method but it both annoys people who are legit (heck I know I hate it's guts) and too easily subverted (a hack neither has to necessarily modify the program or be in the same folder as a game, because it works by using an array out-of-bounds abuse to modify memory and hijacking STDIN of the keyboard etc).
The only thing you would want to check for is legit models/skins anyway. Some aimbots rely on unique or specific colours as a targetting method, and the way that works is if you modify or replace the model and/or skin.