Hi Daywn,
It would be a good idea. If you went with a 4" eurobrace and one 8" crossbrace - you'd have two openings that would measure 40 x 28" and the tank (if made well) would last a lifetime.
You *could* eurobrace it without crossbracing, but IMO in order to keep the structural integrity and deflection rates down - you'd have to make the eurobrace too wide for it to be worthwhile (roughly 8").
HTH,
James