Rails, Bed - add additional, 2nd, rail set below OEM rails?

Has anyone tried to add, or successfully added, a second set of bed rails below the OEM rails? The BakFlip cover has 'hidden' original and I want to add second set of rails 3" to 4" below the original rails. I want to be able to use of tie-downs, bike rack attachments, etc.

My truck has factory liner/rails installed (tacoma, dbl, longbed, limited).

 

Just use something like this. Cheaper and more useful. Like Toyota should have done in the first place instead of using a half ass proprietary setup that generally sucks. http://www.coretiedowns.com/product/tie-down-solutions

 

Thanks - good input and that gives me some ideas on how to go about this.

 

Crom's posts in this thread have a lot of good information. http://www.tacomaworld.com/forum/2nd-gen-tacomas/28533-installed-d-rings-bed-pics-26.html