Seems like a huge waste of silicone, while adding more chances of failure. When using silicone for air tight seals, you should apply just 1 continuous bead, else there may be air pockets between the beads. If you have more than one bead, when you install the glass and squeeze out the excess silicone, you'll be squeezing out more silicon than necessary and leaving a large air gap in the middle. The more beads of silicone you use, the more impossible it is squeeze out air bubbles and get an air tight leak proof seal.
Also remember, the tooling time with silicone is only about 5-10 minutes. So the clock is ticking to get this done before the curing process begins. You shouldn't try to go back and spread it out perfectly evenly with a putty knife either because of silicone's tackiness. Trying to spread it out evenly might actually just make things worse, especially while that tooling time clock is ticking down. The less you touch the silicone bead, the better. You want to get one nice even bead. The thickness of that one bead is the only variable. When you put the glass on the one bead of silicone, you evenly flatten out the silicone bead, and air escapes from both the sides along the joint, leaving an air tight seal.
Silicone has excellent tensile and adhesion strength for most glass / aquatic applications, so using more than necessary doesn't really help. If it's not adhering well to the material, then adding more isn't going to really help. It should be like a good weld, where the welded joint is actually stronger than the material itself. (Like you, I have a strong background in welding/fabrication) If silicone is applied properly without any air gaps, you're more likely to break the glass accidentally, than to have the aquarium fail from a silicone seam.
If the thickness of the silicone gasket is still a concern, you can always add a single silicone fillet around the perimeter of the glass, so that there is 2nd air tight barrier to prevent leaks also. You have to wait for that silicone gasket to cure before adding that 2nd perimeter layer though. For that silicone perimeter, it is ok to touch it up and spread it out evenly with the back of a spoon or your finger, before it starts curing. You got to be quick though. The less you touch it, the better.
