My way
a make a surprise check of the equipment carried by the players about every 4 levels. If they're caught using an incorrect weight category, they're force to carry all that equipment around for 2 other levels, facing all the penalities.
It works :)
Bye
Fabio
Sudgestion
Monte cook, in The Book of Elditch Might, uses a feat for similar effect. Basically the cost is 30(instead of 25)X C.Level X S.Level, and you have to be 5th level caster to take it. It's Etch Item or something similar.
Bye
Wyr