sress/strain guages on each load bearing member of the gear would probably be a better way of doing it, v. light and cheap and accurate.
Retro fit would be relatively straight forward installation wise, as there would already be a wire going into the fusealage for brake temp etc. Tricky bit would be calibrating it, as you'd have to weigh the whole airplane to get a base figure to work from, for all I know this is done anyway, but I bet working out the how the stresses (ie weight) effect the reading got from the guages would be fun, lots of fun with load bearing items at funny angles.