All of our club boats are stored inside. A couple of years ago we had a refit in the store, as we had 16+ more boats that we needed to store & little additional space for them (photos below, are from that time). Canoes & SUP boards are stored all together towards the back, along with the trolleys. Whilst Kayaks, Paddles & other boats are stored towards the front.
Each kayak "cage" has three rows of kayaks & each row is strapped together, to prevent a giant game of dominos from happening (which has happened a few times, previously), when boats get removed. One cage holding Play & Kids boats, another Touring, SOT's & Comp boats, one that holds boats that can't fit into the others & finally the last holding the WW & GP boats. Four kayak "cages" in total.
My old university group has/ had a similar system, back in the day. They had individual bays made up of scaffolding poles/ wood, which would house individual boats. At the very back, they had four shelves for boats, that were too long to stand upright. The Duo &/ or wavehoppers would sit above the play boats.
Their buoyancy aids & decks were kept on hooks, within their store. It was fine & kept them out of the way when not in use. However once people were trying to grab boats & other kit from the store, particularly when numbers were high, it became a little manic.
My current club keep Decks & Buoyancy Aids on Trolleys, which get wheeled in & out at every weekly session & stay in a corridor we made, between the boat cages. Trolleys that hold the cags & BA's have metal hangers that can't be taken off the trolleys. Paddles are stored in wheely bins & again, get wheeled in & out, during weekly sessions. Definitely helps reduce the amount of people, in the store.
Somehow they all fit (& hopefully we have a bit more space, for a few more boats soon).