Congrats upon your transition to the dark side :-)
You are an experienced sea kayaker with the seamanship that comes with that. That's already a great asset. No doubt surfskiers have a different approach to safety compared to seakayakers. By the time we have finished schlepping tons of safety equipment, stowing it in various compartments and donning all our gear and then go through a beef breaching, most surfskiers are already 2-3 miles out to sea. That's the beauty of surfskiing: go light, be fast. I thinks that's where its main strength lies, speed. Trying to even remotely reproduce the safety equipment of a fully loaded sea kayak in a surfski annihilates the advantages (and fun) of a surfski.
That is not to say that surfskiers aren't safety conscious or don't possess good seamanship.
For daytrips beyond 3-4 hours, I carry a storm cag in a drybag under the bungees behind the bucket ("cockpit" :-)). If I go further out or if it's colder, I wear my sea kayaking PFD with all its attached safety gear and reservoir rather than just my much lighter surfski PFD. I don't eat much even during longer trips and just carry 2-3 Cliff Shot Block bars in my PFD. I see no good way to store a spare paddle. Spare paddles in my personal experience are for medium consequence-low probability cases. You can always paddle canoe-style. If I'm not close to sore I wear a paddle leash (paddle to boat) AND belt leash (me to boat).
At my level of surfski expertise, which I consider at the low end of intermediate at this time, planning in regards to sea state and weather is key. Whereas I would go out in 25 kn winds and higher sea states in my sea kayak, I would not in my surfski, not yet (downwind runs in > 25+ Kn wind are what surfskiing is ultimately all about). Therefore, stable seas and wind are a must before committing to a longer run like yours, much more so than in your sea kayak with everything including the kitchen sink in it.
Of course, your stability on the ski ties directly into all this. Whereas an expert is faster in an expert ski (21' L, 14-15" W), someone like me will be relatively faster in a wider, more stable ski (e.g. 19"L, 20" W). Relative to myself in a narrower ski that is. With a little bit of training in an "early intermediate ski" you can cruise at 5.9-6.3 mph (statute) without too much effort for the distance you mentioned, especially if you go fitness-oriented. If you get significant help from the tide, you could make it around in under 3 hours (of course you may have to wait for tide reversal).
Do make sure that you have a reliable remount in the conditions you paddle in. A very fast remount in shark territory (one major disadvantage of surfskis without compartments: one bite and you flood. I went out to 1/2-Way Rock out of Manchester in early April and splashed on the way back near the seals. That was a couple of months before I heard about increasing great white sightings in Salem Bay).
If there's a stable weather window, go for it. Of course, dry suit and gloves w spares and head gear in November, which goes without saying.
I don't think you're missing much relative to "surfski dudes in winter without PFD or wetsuit".
Just my 2 cents. There are some much more experienced surfskiers on this forum who could give you advice.