I'm in the process of working out equipment for my SIB (2.7m airdeck). My usage is in sheltered waters, never more than a mile or so from shore but several miles from my recovery point. It's basically a bathtub sized thing. Scaling down from offshore cruising is tricky - but one has to be sensible as to what can be carried.
My Likely Incident Scenarios are:
1. Engine failure
2. Capsize (very possible in this pocket rocket
2.5 kg Bruce Anchor, 4m of 6mm chain and about 75m of fine braided line - currently in an small cordura sports bag but in a larger boat it would be in a flap draining bucket. I have a small bailer in the bag and a sturdy plastic bag to line the sports bag to act as a big bailer. There is a very small fender in there too, in case I need to ditch the anchor line in a hurry when fishing.
Sturdy painter and large Carabiner - anchor chain can be clipped to this for quick beach mooring.
Small tool kit - sufficient to change plugs, repair starter rope, mend fuel lines.
Spare fuel primer bulb and jubilee clips, cable ties, etc.
Clamshell puncture repair gadget. This means a pump too - looking for a good solution for this. Small cheapie pumps seem to be pants - any ideas?
The ground gear goes in the sports bag in the bow - keeps it down a bit.
Everything else goes in a 1300 Pelicase which is on a 1m lanyard. I have a small compass, GPS, divers torch, killcord, two smoke flares and a tiny 1st aid kit in there too. There's still spare space for a few energy bars, phone, car keys, etc. It's amazing what fits in a 1300 pelicase!
On my person I have a VHF and a PLB, maybe the torch if it was later in the day.
I don't carry spare fuel as the tank is 12L - the engine can only burn 4.5L/hr at WOT so almost impossible to achieve an empty tank in the few hours one wants to be in an inflatable bathtub for....