I'm thinking of building a mattress platform with space underneath for storage
BUT what happens if you have a flat and need to get to your spare quickly?
Has anyone here had this experience, and if so how did you handle it?
I made a platform in part so I could carry a full size spare. That tire is secured to one of the infloor seat mounts under the platform. I would have to partially dismantle the platform to get at the tire. So it is accessible but not quickly.
Some time after building the platform I realized that I couldn't get at the compact spare without completely removing the platform. So I replaced the plastic lid with a custom wood one. The opening in the new one is only 2x2, giving access to tools that I now keep in the spare well.
Among those tools is a good tire plug kit. I've had occasion to use it once. So between that and the air compressor I haven't had to get at the spare at all.