Thanks Shabby for the pictures.
I have the lead tape and have it applied oon the base, but I like how you've done it. Another similar technique I've seen to yours is the way Jimbo places the thin magnet material under the player platform in the exact same way as you've show. I think the lead tape is slightly thinner than the magnet and obviously more dense. With the putty AND the lead tape, the nice thing is that you are putting weight low in the base which makes the figure more stable (and more balanced).