Houston Trailer Storage - Covered vs Uncovered?

Same as in Calgary, protection from sun and water.
Depends on your use. If I was using it 6mo out of the year I wouldn’t spend more to cover it the other 6 unless from solid rain/snow. If it’s used that much, its less ROI if you’re paying for storage.
Remember too, covered storage is handy, covers and tarps aren’t, but they’re effective and cheaper.