Not familiar with New Wave, but Blue Tube has some pretty deep spirals. My early efforts using Elmer's Wood Filler were disappointing. So I tried an Apogee suggestion of using the epoxy clay that they sell. The results were quite good, but it is a royal, time consuming PITA.
I use a single edged razor blade to press the epoxy clay into the spiral, then dip the blade in a little rubbing alcohol before using it to smooth the epoxy. A little sanding after the epoxy cures and it's ready for primer - but doing a long, large diameter body tube can take hours - I sometimes need to take a break simply because my fingers start cramping up