thank you, Rick, for the comments on my team and for the advise
I think you're right for the plateforms. I've got thin plasticard which should do the job perfectly. On that team (and the future steelers team for my brother) I'll keep the "new open rules" 3.6 - 4.0 -4.2grams, and for "super heavy mammoth" players (defensive, for example) I'll use your tip to make them 4.2g legal.
One of my future 2010 projects is to make a "super detailled" 3.3grams legal team, real 28mm scale (like fab5), BTW !