Built up one of the SunRingle Mulefut rims yesterday. Went ahead and taped it up and put a tire on as well. A few thoughts:
I put one layer of the Hello Kitty tape on inside out to show through the cut outs (customer's daughters are really into Hello Kitty, so does this because they get a kick out of it, he supplied the tape). The tape was just wide nough to overlap the spoke nipples. Then I put a 1" wide strip of Gorilla tape along both bead hooks, it's wide enough to reach the sidewall and overlap the spoke nipples. The rims are actually double wall right at the bead hooks, and there are vent holes drilled there, so the tape needs to stretch from sidewall to sidewall to cover all the holes. Finally, one more layer of hello kitty tape (sticky side down this time) right down the center. That means there's no sticky sides of the tapes exposed anywhere, and there's three layers of tape over the spokes - I was worried about them puncturing through a single layer like Sean mentioned. Three layers still may not be enough, but I was trying to avoid using a rubber strip if possible to keep weight down. Only time will tell...
Mounting the tire I have (a VeeRubber Mission 4.0", tubeless ready/sealant compatible or whatever they call it) was easy, I needed just a little help from a lever to get the last bit on. I put a tube in and pumped it up, and the beads snapped into the bead hook with a light 'pop'. I let the air out of the tube (which takes forever! haha) and the beads stayed in place. I then pulled the tube out, leaving one of the beads locked in, and tried to pump the tire up tubeless. I don't have a compressor however, and couldn't move enough air to move the tire. I'm going to borrow a compressor tonight and see if it'll push that other bead into place.
So the bad news, which I expected with those HUGE tires, is you will need a compressor to seat them, you just can't move enough air with a floor pump, even a high volume pump and removing the valve core for more flow. Doesn't even make the tire flinch a bit.
The good news, once the tire lock into place, it will stay there. I had a really hard time getting the tire loose from the bead! I had to lay it down flat on the floor and push as hard as I could on the tire sidewall, putting all my weight into it, and then bounce a bit, before it finally let loose. That's good!