think you got tank dimensions wrong lol you had 48 1/4 W x 12 3/4 L x 21 H
I rounded up the height .
they should be 48 1/4 L x 12 3/4 W x 21 H
I would go with a 3ft tall stand
this would give you a overall height 4 ft 9 inch tall perfect height to do maintenance and view the tank .
I estimate 7 studs 2x4x8
this is the stand I built for my 90g
you can paint it or wrap it like I did
the finished product
If you build it right it will be a very sturdy stand that will last forever
I built mine in 4 prefabbed sections making assembly simple and strong
I also added laminated floor boards to finish it it off optional
I used 2 3/4 inch deck screws to secure everything together