Not Flex tape but I have successfully used white Eternal Bond tape to cover minor tears on my rubber roof and had no leaks and the tape lasted for many years until I sold the trailer. Also used the same tape to cover a foot long narrow gash from road debris on the very low front left side of trailer just above floor frame. Again the tape prevented water from entering the TT and tape blended in well with white side of TT. I love Eternal Bond. Easy to use and work with and sturdy long lasting.