Ideas for securing an outdoor under stair space

[_jkl_]

Hi there,

I'm looking for ideas please on how I can make this external under stairs space secure to keep, among other things, my road bike. Currently full of rubbish from previous owners but will clear out this weekend!

Searching on google I can't seem to find many options for angled shed doors (diy) and advice about how / what to hang it to. If you can see from the photos, there is one fixed wooden bracket on the right which might work, but what options do I have for fixing a padlock, for instance?

Inside, I would like to fix some sort of ground or wall anchor to lock my bike to...

Any ideas are most welcome - thank you.

[big-all]

my thoughts
assuming the door can be fixed to a frame say 6" back
why not just go for a open top above a door with perhaps a 10" champher on the door finishing about where the crack is on the stairs above

[Grendel]

Exterior ply cut to suit , at least 18mm but doubled up might be even better , heavy duty hinges with bolts and a hasp also bolted . Simple enough.