Look into the 'anti-dive' mods Gold Coast (I think it was) did to the front bushings.
The problem comes from loading the front and the back coming up. Reduce the amount the front dives and the geometry stays more predictable. Or that's the theory.
Another option may be to give the rear more braking power. An adjustable proportioning valve or using larger ID front brake lines (which would reduce braking pressure). But both these must be very well understood before attempting any modifications.
The negative results could be VERY dangerous.