First, @Marc_T, under no authority I’m awarding you Best-Written-Post-as-Engaging-Short-Story prize for 2025!
I generally handle these in My Tasks in one of my existing sections there (see my Tips and Tricks > Forum Leaders tips Your Simple (or Advanced) Strategy for Asana’s My Tasks). If you prefer, you could create a One Offs section there too.
Or create a One Offs project if you like to have a task always in a project. A project like this is perfectly legit!
Thanks,
Larry