I've beaten it now. The actual solution, in the end, didn't seem too tricky; but based on the difficulty I had finding it (and so did Crane, it seems), I'd still say it should probably be moved to a later rank...
Frenzy is definitely my favorite rank so far. Almost entirely good levels here, and even at worst they're "okay", not "bad". A lot of them are short, puzzle-type levels, which tend to be my favorite.
It'd also seem, based on the comment, that my solution is different to Crane's, because...
Mine did use the mesh/ball tower.
EDIT: Indeed, my solution is
very different from Crane's, apart from the very end bit.