[Chris is me]

Putting these absolutely massive pockets on all sides of your drive tube is making your frame weaker at the exact points where you want it to be strongest, and leaving strength in the rest of the tube where it is less critical. Clearly you're trying to put power transmission in the tube, but if you feel you will need access windows that large to do maintenance, there's no use even bothering to put it in the tube at all.

You've got the open ends on each end of the tube for access. Maybe cut one hole in the middle if you really think you need it, but not these very large holes on all sides of the drivetrain. You have to either compromise accessibility / ease of maintenance or you have to compromise by putting the power transmission outside the drive tube - right now your point of compromise is chassis strength, and for what benefit that is for is unclear.

Ideally if you are putting power transmission in a tube you want it to be a low maintenance system. This is why exact center drivetrains with belts (or chain) are commonly used with this type of setup - with belts you install it once and then you're set.