ClustersBabyMama - KnuckleHead is right in the specs, but not in the reality on older ones.
They will support the weight, but check the flooring. Mobile homes are not on Foundations so moisture gets up on the bottom side of the flooring and can weaken it dramatically compared to your standard home.
As long as you check and make sure the flooring is solid you should be okay. If you are still worried, locate two of the Steel I-Frames and place a piece of Particle board the right width, etc.. to lay over them and match your stand. Then put your tank on that.
I have a 125 Gallon in my Living in a single wide and a 55 Gallon in my bedroom with no problems to date.