Short cuts have a way of turning into long cuts, and by removing the center brace, you may end up starting a long and complicated adventure. Even longer than the one you didn't want to emulate. We would all want to read and see the adventure, but like gawking at a car accident in the other lane, it would be better if it didn't happen.
Why? There is a prime chance that removing the brace will cause cosmetic damage to the stand. If you have to saw it out, it will no longer be the same size when you replace it, and the damage will be more than just cosmetic then. Also check all your measurements beforehand to be sure the new sump will fit and all the hoses and fittings needed are on hand, maybe some extra parts too just in case.
I would get a couple clean plastic trash cans. Make up your water change water at least 24 hours in advance in the standard container you already use for that. Add clean water from the tank to each clean plastic trash can. Remove the live rock to one then catch out the fish to the other and then add a few live rocks from the first trash can to that one ( a step that keeps the fishes' water a little cleaner), and start an airstone in each trash can.
Lift the empty tank off. Replace the old sump, using as much of the old filter material as possible without cleaning it more than shaking off debris. (If you plan to replace the old filter material, do that in a week or a month to reduce the number of changes going on at once.) Turn off the airstones. Replace the tank which you might clean up a little if you want, and add water from the upper levels of the trash cans which has settled out a little with the stones turned off. Replace the live rock, add more water until you are down to the debris layer in the trash cans. Consolidate the trash cans into the fish one. Restart the airstone for that one. Top off the tank with the water change water and get the sump started. Add the fish. If you didn't quite make up enough new saltwater, wait for the remaining water to settle out and use the clear part. It is important not to overclean, but removing debris especially that settled into chunks in unseen spots is fair game.