Feniex makes flat window brackets. They use 3M VHB tape. I've seen some in Jeeps.
Another route would be to adapt end brackets with suction cup feet.
I've used it to hold T3s on brackets to the headliner of a 2016 Tahoe. Not a fabric liner but a hard surface with stippling. Been holding for 2 years. It's in one of my install threads somewhere.
The brackets I saw were stuck to the window and the light head sat on it like a shelf. Ultra bright lightz sells them.
View attachment 220714
I've used it to hold T3s on brackets to the headliner of a 2016 Tahoe. Not a fabric liner but a hard surface with stippling. Been holding for 2 years. It's in one of my install threads somewhere.
The brackets I saw were stuck to the window and the light head sat on it like a shelf. Ultra bright lightz sells them.
View attachment 220714