Yeah, I've finished padauk a few times and this problem sometimes rears its ugly head. A sealer coat is a good idea. Can polyurethane actually cure on a lacquer base coat? I was wondering about a shellac sealer as a possibility, too.
I have noticed the staining ability of the padauk dust, though I've never used it on purpose (only happens when I'm trying to finish a piece and the orange bleeds onto a different wood... ugh). Can you actually use it as a disc dye?
My previous discs were made out of honduras mahogany and walnut, and had no trouble finishing. But padauk is a beautiful wood, so it's worth it.
I'd be interested in seeing some pics of your boomerangs. I love seeing wooden items for some reason.
Compatibility is a big deal, but finishes available now give us more options. I'm a little out of the woodworking game now and honestly I can't recall what lacquer I was using at the time. I know none of it was Deft, because I hated that waxy stuff. lol. Carver-Tripp was what I ended up using and they had a fantastic water-based urethane. If I remember correctly, a dewaxed shellac is ok under lacquer, but not under traditional urethanes where they will tend to curdle instead of curing. Another neat option are soft waxes and long dry oils...low sheen and silky. A friend of mine turned me onto an old shipbuilder's finish, too, which I think was made of vinegar, pure tung, and turpentine (have to look that one up again). Plastic finishes are shiny and much more durable, of course, but with some woods a softer finish really looks better to me.
Actually I did try the padauk stain on a disc awhile back because of a thread in the dye forum. It sorta worked - a little - but I wouldn't recommend fooling with it. The color was way off and it didn't have staying power. I hoped that it might do better but I'll just keep using my stockpiles of rit. I don't have any pics of the solid wood, lapjoints, and natural elbow booms I made...all of those were given as gifts or donated as tournament prizes. I'll see if I can find some links to others' work to share with you, though - lots of great craftsmen out there. The majority of mine are made from the ultraply Finn birch plywood, phenolics, and a few plastics since I've been more of an advanced sport & competitive thrower instead of a craftsman woodworker. They're fun...great sport when it isn't windy!