Does the tank have a frame? Is there any way to add some angle iron across the front span under the 2 by 4 ?
I think you would probably be okay but if you could reinforce the span it would be safer.
I would just double up my 2x4 stringers and call it a day
Yeah if you have space to double up on the 2x4 you could do that.
If it were mine I probably wouldn't do anything to be honest. Most of the weight will be supported by the vertical legs.
Ya and then 3/4 plywood ontopSo just add another 2x4 length wise?