Very good idea. This is the order in which MPQs are loaded (did it on wine) :
archive Data\enUS\patch-enUS.MPQ opened
archive Data\patch.MPQ opened
archive Data\enUS\patch-enUS-2.MPQ opened
archive Data\enUS\patch-enUS-3.MPQ opened
archive Data\enUS\patch-enUS-I.MPQ opened
Unable to read extra attributes: "Data\enUS\patch-enUS-R.MPQ"
archive Data\enUS\patch-enUS-R.MPQ opened
archive Data\enUS\patch-enUS-Z.MPQ opened
archive Data\patch-2.MPQ opened
archive Data\patch-3.MPQ opened
Unable to read extra attributes: "Data\patch-A.MPQ"
archive Data\patch-A.MPQ opened
Unable to read extra attributes: "Data\patch-R.MPQ"
archive Data\patch-R.MPQ opened
archive Data\patch-S.MPQ opened
archive Data\patch-Z.MPQ opened
archive Data\expansion.MPQ opened
archive Data\lichking.MPQ opened
archive Data\common.MPQ opened
archive Data\common-2.MPQ opened
archive Data\enUS\locale-enUS.MPQ opened
archive Data\enUS\speech-enUS.MPQ opened
archive Data\enUS\expansion-locale-enUS.MPQ opened
archive Data\enUS\lichking-locale-enUS.MPQ opened
archive Data\enUS\expansion-speech-enUS.MPQ opened
archive Data\enUS\lichking-speech-enUS.MPQ opened
There are non blizzlike patches in the list. I guess A, R, Z, and I aren't.
I will confirm if it works later (maybe in few weeks) but that looks very logical to me, so that should solve it, thanks a lot !