Hi Jason. Sorry I haven't responded sooner as I was out of town for a few days without access to a computer.
Good thing you added that middle support as per the Doc. Yes, the light grille is a tad brittle and wet media is heavy, so middle support is critical.
yes, a 30g barrel is the same height as a 44g barrel. Believe it or not, the 100g rubbermaid stock tank is the same height as the 150g one, too. So, given that do go with the extra filtration, you won't regret it.
I don't have any more photos on that barrel than the ones I already posted on my barrel thread. Is there something that you are looking for more information on?
If I'm catching your drift correctly, it sounds like you are saying your 55g barrel is going to act as a settlement chamber for your stock tank? If I have that correctly, that is an extremely wise move. I think many people do not realize the incredible value of a settlement area in their filtration set-up as a method of pre-filtration. It does wonders for water quality--especially if you are gunning for that "gin clear" level most of us fantasize about. It also increases the life of the pump because less is getting to it. Not to mention, you preserve the quality of your main filter so it can do it's magic with the bacteria rather than being slogged with muck.
As long as you got a good waste pipe on your settlement chamber so you can easily evacuate crud easily, it really just becomes a simple routine task.