You might be creating some pretty significant balance issues putting all of that on the right side. My superjet was unbalanced and it really affected the handling. See how it handles, but here is how I fixed my superjet in the event that you have a similar issue.
I bought a used weight for it. It is a piece of aluminum that goes between the two motor mounts. It's 1/4" bar stock that has the other sides of a box welded onto it, then before the top is put on it, they poured in led. It weighs about 6-8 pounds. It made a huge difference in handling. All I had to offset was the battery, but it worked really well.
Great work on the mounts. Wish I had access to a waterjet. I have some projects I really need to be able to cut aluminum and polycarbonate but I don't have access to anything and one-offs are expensive.