Use the Wow Model Edit loader, attached below. Put it where your wow.exe is at and use that to launch wow.
Also just keep your custom MPQ patches inside the Data folder, not the Locale Folder(deDE,enUS,ruRU,enGB,esES, etc). And name it using the patch-3.MPQ , patch-9.MPQ, patch-B.MPQ, patch-F.MPQ, patch-Z.MPQ method of naming.
Also just a tip, It is in your best intention to not modify blizzard MPQ files. That could lead to some pretty crazy(bad) results sometimes(such as reinstalling/downloading the entire install.)
If you are already using WowME and still getting the error, then upload your patch and we'll see if we can make anything of it.
Also since you said you modified your 2.4.3 client.... does the game load fine without your custom patch?