I don't think it's a good idea.
If you load say 100kg, the impact of collision becomes concentrated in a very small surface area. I am no expert, but imo this would accelerate damage to the your plates. Especially if you only use 10kg (close enough to 25lbs) bumpers, they are quite thin.
You want as much surface area as possible to spread out the force.
As PBandy suggested, try to get fatter plates if you can.