One thing you might want to do is check your floor for "bounce". That is put the tanks on the floor in close to the location you want them, and fill them up. Then walk, bounce on your toes, etc, around the room and see what happens.
I did this with a 75 and DIY stand. The location was against an outside wall & perpindicular to the floor joists. Despite this, there was enough movement in the tank to really concern me. Bottom line, I also did some crawling and my bottom floor joists are 2X6s. Even with a pier and cross beam not 8 feet from the tank location I could see the floor move up & down more than 1/4 inch when my g/f bounced on her toes near the tank.
Now this might not be a cause for worry structurally, but that tank is not gonna be set up till I address this. Even if it is not a support issue, it drives me crazy. Never seen a house with a 2X6 floor. The funny part is, the upstairs seems to have 2X8 joists. And the floor is much less 'bouncy'.
Your floor sounds much more solid than mine, and you have a good location picked. Still, it can't hurt. Consider it a dry run for later water changes.
Good Luck with the project, and we want more pics!!