fasteners or drilling into frame recommendation

[67ragtp]

I'm mocking up brake lines to mount to my new DSE subframe and want to mount the small "L" brackets to make the transition from hard line to the flexible brake line. What fasteners do you guys recommend, no access to the inside of the frame rails or frame cross member. I hate to use self taping stuff. I think its to thin to drill and tap. Whats your method? Thanks Rich