Just get more cut with a plate on each end and screw em in
then you dont have to move anything...If your skirting it anyways
the weight will go down when its full unless you plan on rocking it I dont see a problem.
My stand is 8 feet and only has a center brace... its 1 1/2" 1/4 wall but still its got 300 gallons on it
And heres my 180 dual rack i made with No Center braces in the top part of the stand...and its a 2 piece so its not even welded together LOL
Rock solid and 1 1/4" I have alot of faith in thicker softer styrafoam to take up that bit of flex in the stand.
All that being said however... I didnt build it so theres no warrenty here LOL