I saw a picture of a rear 3pt weight that was more or less a hunk ( or large poured block ) of concrete with the 3pt pins added in.
Seemes effective.. if not a bit unslightly.
I've also seen some nice front weights. Over in the yanmar area, we have had a few guys design some good ones. One used a military ammo box full of lead scraps, mounted to the front bumper.. one fellow made a mount to add round exercise weights to ( looked nice ) and I built a double pipe front weighted bumper out of some 6" pipe, concrete, rebar, and a bit of hardware, etc.
But the nicely painted rear weight looks premio
Chris