floor worries

Hi all . I am living in a large mobile home not motor home but mobile
home and am in the process of setting up a 55 gal tank. Ive been giving it
some thought and I am a bit worried about the weight. I figure it will
weigh in the neighborhood of 550 lbs or so but I believe that weight would
be distributed over the length of the tank so I would think the floor
would hold that weight . I am wondering if the 120 lbs of gravel that will
be in the tank is displacing an equal amount of water or should I add 120
lbs more to the total weight....... My figuring is, if I weigh about 260
and if I put 3 of me in the same area I am sure it would hold that weight.
I hope I am thinking correctly and that the weight of the tank and water
etc doesnt push down on the floor in only the 4 cornors of the tank and I
find the tank and all going through the floor in time. Anyone got any
ideas that can either ease my mind . If not I can see myself crawling
around uinder the home trying to brace the floor .??????? IDEAS anyone
.....Thanks,.Ron