Calculating PSI at base of pool

I have a 32' x 16' x 4' pool that we have dismantled and put back together. Problem is the bottom track was stolen during the move and I need to come up with an alternative. To replace this track from Kayak would run me well over $1000...

Last year I made a makeshift track with aluminum angle and braced it equally in 2 places in between the longest walls. This worked for the most part last year, but the bottom has kicked out a bit in some places... I am throwing around several ideas of strapping it together at the base (wire cable/turnbuckle combo, reinforced concrete, even ratchet straps...) but would like to figure out what the tensile strength/working load/breaking strength/etc) would need to be of whatever medium I choose.

Basically I know there is approximately 15,000 gallons of water. (the sides are 4' plywood, but obviously it isnt filled it to the brim)

So approximately 125,100 lbs of water.

Calculating the pressure of fresh water at .433 per ft of height gives me 1.73 psi at 4'. Adding atmospheric pressure of 14.7 and I get 15.56 psi. But this is the pressure exerted downward.

Using a formula for Force (using the area of the longest side):

F= 1/2 x density x length x height^2

F= 1/2 x .036 x 32'(12in/ft) x 48^2

Force = 15,925 lbs....

I've been looking over so many formulas all day that my head is starting to spin....

Can someone please help?! And by all means, if you can think of a better way to brace the bottom of the pool (aside from shelling out $1000 to Kayak) - I am all ears!

Marian