OK, just found and read through your thread. Nice digs! If you need help on how to extend your build, I'm your guy. I ordered my 125-gallon Reef Savvy tank May of 2015. It is still not finished. My Pukani rock, which I don't think you can even get any longer, went into a trash can a week or two later. Still in there. Procrastination is my game!
I had a 200-gallon fish only tank 30+ years ago, really a tad before reefing really became doable for most people. I enjoyed it, but got bored with it and sold the whole deal and got out of the hobby for a few years. I did enjoy the size though (84x24x24) and would have liked to have gone with the same size for my "new" tank; however, the wife decided that furniture in our small living room was more desireable.
When reefs became more prevalent, I tried a 75-gallon reef tank. I was hooked and there was no turning back. For me, I would likely not have a fish only tank again. The diversity of life that can go into a reef makes it far more interesting to me personally - and I can have fish too.

A peninsula reef tank would be way up on the awesome scale, because you would have so much more viewing pleasure with two long viewing panes and additional places for corals. If I had it to do again and had a suitable place in my home to place it, that is the way I would go.
It is good that you have a place to try out ideas before taking the plunge. I see so many threads on here that ask advice after the fact. Following along to see where this goes...