There are are number of good sealants out there but just as an FYI, you don't need to throw out wipe-off towels, only applicators. Coatings don't ruin wipe off towels, just launder them as normal.
Ceramics offer plenty of benefits. I won't re-list what most all of them already market but I think in your situation, while I don't have an answer as to why you're seeing water spots, the facts still remain that ceramics offer plenty of up-side and little down side. They aren't for everyone that's for sure.
Not surprising. 99% of gloss is from the polish phase not the LSP, ceramic included. I keep a HUGE portfolio of work on my website and even in person, let alone pics and videos, one would not know or "see" the difference in products I use regularly.
I've had great luck with Gliss v2 and even SiC or GYEON MOHS EVO as a coating. Again, can't say I can fully understand what's happening in your situation. I've been using coatings for years and haven't had issues with water spots except for very hard municiple water like sprinkler at a hotel, etc. since very early on. The newer products I've used area all very good and resistant.
The only real suggestion I would have would be to use a topper like 3D Bead it Up or one of the other many different types of coating compatible products. I've owned no less than 8 black cars and haven't had any issues.