@Mauro, I'm wondering if youve ever considered doing a short placket (3-4 buttons) Henley in a heavyweight bamboo/serona.
I have two of those tees and love them, but also really like the Henley look. I think it could work as something a bit more summery and drapey than your current henleys.
Could this potentially be an MTM item if there isn't tons of interest.
Edit: forgot to mention I was originally thinking short sleeve just like the tees, but long sleeve would be...