“I don’t go out with a tent on Shabbat.”
“I’m glad you’ve found a new chumrah that doesn’t involve putting people down. “
Not a new churmra. A hat with a wide brim (at least one tefach – about 3 inches) may be considered like boheh ohel every 4 amot. Look at Shabbat 138 b. The Mechaber mentions this l’halacha (i think siman 301) and the Rema does not argue.
The MB and others find heterim for those that do wear hats with brim a tefech wide.