After re-reading the original post, I beleive what is being delat with are single peice wheels, rather than the 2 peice split rim. I noticed that it's mentioned that they are leaking around the rivets. Sounds like they might be loose. I have heard of guys peening the tight to get them to stop leaking. You may also consider seeing if you have anyone in the area that can install a vulcanized rubber band in the drop part of the rim, like they do on tubeless wire wheels, to seal them up.

Bill Burmeister