honestly I've never watched mine cycle with weight but if you are getting play I can only think of two things.
1. either that nut isn't tight enough
2. that top strut mount is broken.
With my new Bilstein shocks I have about 1-1.5 inch of thread sticking out the top.
I expect the only weak point of Mark's budget lift is that it uses the OEM strut mount which has shown to be a weak point in the past.