I have had the same luck RTV Adhesive brand new tank I sanded the tank to rough up the surface so it would stick better. They stayed on for about 2000 miles 1 feel off in my garage and the other on the road. I was riding with a friend and lucky he saw it fall off. Try #2 I wire wheeled all the RTV off the covers and then tried to refit with 3m molding adhesive looks like it may work better but the covers don't fit the tank very well I don't know at this point how to get them to stay on.
before the RTV adhesive I also tried 3m double sided molding tape. Same thing i used on my swing arm covers and stock tank guards It wouldn't stick to the Safari tank.
Let me know if anyone comes up with a solution.