Tubeless on Fatbike has been a PITA!

Has taken many tries to get the bead to finally seat! Used a strap around the tire to force the bead to the rim. Figured that one out finally! And the front is "mostly" holding air (a few days)

The rear, so far I cannot get it to seal on the Surly rims! Cleaned w/ Alc. and taped the heck out of it w/ a hair drier.

I thought I had done a good enough job in being meticulous in my attention to detail/leaking opportunities. But guess I was wrong.

Continues to leak out in the cut-outs in the rim.

Was thinking ripping it all out again, cleaning, and using "Flex Seal" vs tape?!

Thoughts?

https://preview.redd.it/7zyg9dt6ngbe1.jpg?width=3472&format=pjpg&auto=webp&s=b2924821b8cc7a3208cec118cd1a6d8de58e6963

https://preview.redd.it/1d272dt6ngbe1.jpg?width=3472&format=pjpg&auto=webp&s=0a614c087e07389b483359a53088d6c2c4fd2e93

https://preview.redd.it/0o6twct6ngbe1.jpg?width=3472&format=pjpg&auto=webp&s=7fc2e61ba64d7bb9390ccda8a4ffdae281865f38