Seat mounting brackets

I picked up a third row seat from a 95 Chrysler minivan to put into my 46 1/2 ton. After removing the sliding brackets and other hardware, what is left are two vertical supports integral with the seat frame. They are towards the ends of the seat, about 6 inches tall in front and 4 inches at the back, 15 inches long, and when mounted level give the seat base and back the proper angles. The front of the seat needs to be 15 inches off the floor. So, I am trying to form a mental plan of how to make brackets.

What I'm thinking is an inverted T bracket on each end to bolt to the floor and through the seat supports, the length of the existing supports. Would aluminum work, or steel better? What thickness? How wide at the base to distribute load? Any other ideas? The seat cannot be adjustable due to there being too little room in the cab.

Weights involved are seat 65 lbs., me 190lbs, wife 135 lbs.