My understanding is that it is actually better to have holes in the bottom of the tank than the side, from a strength point of view. The tech at a glass manufacturer has said that if you drill the bottom of an aquarium it is completely supported, whereas on the side it isn't.
I planned to not have any leaks!! I used silicone to seal the bulkheads. As far as maintenance all the bulkheads are easily accessible from under the stand, unlike my old setup which had holes through the back which were completely inaccessible.
Every bulkhead has a valve of course.
The bulkheads;
Rod.
