Yeah, you can't let them sit. If they are race only and only a couple times a year, yes - take them apart and assemble them before the race.
Personally, I:
- Rotate my spare wheels every week or so (especially in deep winter where they don't get much use) and ride them at least once a month.
- Put tubes in tires that get limited use. Some of my older bikes don't get the seat time to warrant tubeless.
Other alternative is to get a non latex sealant that doesn't dry up (slime).