Shemander raises some good points, especially mentioning spare cotter and clevis pins.
As to lights: A 16' boat, under sail, does indeed not require navigation lights but there must be a torch to shine on the sail when another boat approaches. However, under power, full navigation lights are required. It is prudent to have navigation lights on any boat at night, required or not (rowboats, I suppose, excepted).
As for "too much crap": I'm Murphy's favorite lab rat. The one thing I leave on the dock will become the one critical need before I return. I've became a belt-and-suspenders man due to life lessons -- and Murphy. Properly stowed, I don't believe my list constitutes too much. Another poster was kind enough to share a link for a book about two (of his friends?) who used a pair of Compac 16s as cruisers for an extended trip through the Florida Keys. I'm not even approaching that level. On the other hand, remembering where "it" is, is an issue. I can remember three years old but I'm having trouble remembering breakfast. Labels, labels, labels.
Getting home with sails: Do I hear a bit of superiority here? Shemander, take a look at a nautical chart for the ICW from Ft. Walton Beach harbor to Bayou Chico in Pensacola. When the Yanmar 10hp completely lost oil pressure at the entrance to the harbor, I sailed my Bayfield 29 back to a boatyard in Bayou Chico, in very light air, a good part of it after dark (and reported to the USCG that the Bob Sykes Bridge from Gulf Breeze to Pensacola Beach was entirely bereft of clearance and channel lights). Not Joshua Slocum, but capability. In all my sailing days I've never failed to get home on my own except for one time I misread the channel in an unfamiliar canal, hit a very soft mud bottom, and had to get pulled off, heeled over, with the main halyard. But if there's no wind, it's hot as blazes, and a plug fouls, I'd a damn sight rather be able to change it than sit in the sun until I get heat stroke.
150' of anchor rode: It's not the depth, it's the scope. We have microbursts and sneaky summer thunderbumpers that can gin up 40 mph winds in a jiffy. Fifteen feet of water -- and a lot of our water is 25 feet -- gives only a ten-to-one scope and the light anchors our small boats carry don't hold well in our sandy bottoms, which need a deeper bite to set well. The lower portion of Mobile Bay is know for square three-foot waves when a northwest wind's been blowing for a few hours. Mean depth there, eleven feet. I don't want to be limited to a ten foot rope when I need eleven to be hauled up out of the well. Fifty or even a hundred feet of five-eights rode doesn't take up significant space than 50.
The battery: You have a point there. I've made accommodations for a Group 27, ridiculous overkill, but it's what I already have on hand. The issue will be that it will stow were I would ordinarily put a reserve gas can. Hmm. I might do better with a motorcycle battery secured immediately under the companionway. Thanks for raising that issue.
Flares? True, holding one over the boat risks marring the fiberglass but isn't going to set it on fire. Yes, they do get damp and unreliable if not stowed in something as simple as a Ziplock bag and they have a nasty habit of being out of date when the USCG or the marine police takes an interest. I'm probably out of date here. LEDs have become de rigiour since I got landlocked. Good suggestion as a flare substitute. But you seem to be aiming at a minimum level just to be legal. I'm belt and suspenders, remember. I trailer with a hydraulic jack and 70 lbs of tools.
See ya on the water.
Bedding: Your suggestions are very reasonable. I was thinking more of something cushy for my old bones to lie on, and keeping warm. No sheets. Did I mention pillows? Not sure. If I did, nonsense. Type IIIs with a towel over them work fine.