baffle dimmensions can vary based upon what skimmer is being used, i would suggest waiting till you pick your skimmer, also measure your 55 gal.tank for exact measurements. i usually have the glass cut 1/4 inch short so i have 1/8 on each side for silicone.
yea your probly right. i might actually use a 40b, when i was looking for one i couldnt find one that was a looong drive, and of course they pop up now. i just think it will fit better and keep more room under stand