I'm in a similar, much more open-minded and enthusiastic situation, compared to the OP. I have the 3ft bigger sibling (Catalina 30). Difference being things like, I don't want to start installing too much storage shelves that may negate the reason that space was put there, or make my boat more of a closet rather than a functionial-sailing-island-of-enjoyment. Also, I have been saving for and looking forward to living aboard for the last 7 years. It's not a decision I was rushed into, or made for purely 'romantic ideas of sailing lifestyle' reasons either.
Anyway, another benefit and difference is that I've afforded about 2 months of still living on land, until the lease expires, while the boat is docked a mile downhill. I know.. pretty sweet deal. So I've been able to take my time and measure the storage bins I want, pack what I want to bring with me, and what I will be taking to family during Thanksgiving and leaving in a garage.
My suggestion regarding living on it, is to at least get a marine electrician in there to update wiring to be suitable for whatever appliances (Microwave?) and things you need (GFCI outlets?). Hopefully you have facilities on shore for showering, maybe a storage locker. My greatest fear is electrical- it's the only thing I don't know much about -that something will spark and create a fire, or draw too much power and screw up everything. Might be a couple hundred dollars but you'll learn a lot watching the person, and have a piece of mind. Get a small dehumidifier. It heats the boat, but not too much, and helps keep it dry.. they're like $40 and run 24/7.
Something I think I'll do is run a heavy-duty outdoor power cord (with circuit splitter at the end, like you see at computer desks) from my dock box, alongside my shorepower cable, and into the cabin and plug in extras into that. For example, my TV/DVD, charging my laptop, a fan while I sleep, etc., and thereby cancel out relying on my outlets as much as possible... just a thought.
As for storage, smaller bins are better, if you can work fitting your things in them, because when the time comes to move them out of an area -to work on something- it's nice to be able to spread the stuff out whether than have 2 or 3 enormous bins that need to be piled somewhere in the way. It the C27 has little nook/cranny storage space along the inside of the hull, I would definitely get water resistant/proof bags and store things that you don't need often in there. I bought these large zip-lock zipper bags that are meant for storing bedding, they're huge, they can be bent and stuffed into the oddest shaped storage areas.
I guess one important thing is whether you plan to sail often or not. That will dictate how much you keep on the boat and how you organize it. If you want to sail a lot, but don't want to spend an hour+ of time moving things around to get to safety items (life jackets, paddle?, docking pole, whatever) then it takes a lot of creativity. I am trying to keep the rear of my boat reserved for sailing-specific gear (cockpit cushions take up 30% of it, and my surfboards take 30% because it's the only place they fit) because it is easy to access when I go down below while sailing. Then the V-berth is where my personal items are in bins (a couple of shoe-box sizes, and a couple shallow, long ones that are designed to slide under beds). The dining table is going to be my bed, add a cushion across the isleway resting on properly-heighted storage containers, and laying sideways its beam-length it's larger than my queen bed. That's the plan, at least.
Living aboard successfully and functionally expresses the persons tolerance for small spaces (even on 40,50,60,70ft boats) as well as their creative intuition for solving problems that erupt from it. It's REALLY awesome to see people do it well. It's going to be hard to liveaboad cheaply, so I hope that's not why you're doing it, and to sustain that lifestyle that makes it fun to liveaboard, unless you're able to churn out an amount of money that is likely more than if you rented a studio on land.
I certainly hope you (the OP) are able to make it work, sounds like you're creative and a DIYer so the storage thing might just take trial and error until it's comfortable. Excited to start following your site about real liveaboards too, can't wait to join it.
I guess if none of this is helpful to you, at least other forum readers got to know me a little and reference how I'm approaching the liveaboard-space solutions, these posts stay on here for years don't they? Make your goal to make it appear as organized as smackdaddy's pictures, but still be able to be living on it every day.