Question Heavy duty slides

[bigyankfan]

I want to put my 35 gallon acrylic sump (~400 lbs.) on a sliding platform to make maintenance easier. I want to use undermount slide and I found the Accuride 7950 that I want to flat mount, the problem is that each pair supports on 150 lbs. so I would need to buy 3 sets. Does anyone know of a set of flat mount slides that would support that much weight and if any has tried this before? Thx.

Eric