Yes, lots of thoughts. Designs? That'll need a lot more thinking.
There's a snag: rowers will only adopt something if they think it has
"style". Real "content" is, I fear, much less important.
There might be mileage in the aerodynamic aspect that you propose (&
it's just the kind of practical suggestion I'd have expected of you,
John), but it'd still get nowhere if sold as a safety enhancement.
Still, riggers remain a secondary safety concern in a sport in which, we
go everywhere backwards & unsighted in craft which, with crew, can weigh
more than a small car. Our first concern should be the bows, but that
gets short shrift in nearly every boat - consider how useless is a
typical bow-ball, often badly perished & held on to a lethally pointed
bow, as it so often is, by a bolt, screw or Duck tape.
The best contribution from rigger-makers would be to remove all points &
sharp corners. Sadly, it's always cheaper to weld or bolt a rectangular
block of metal onto the outer end of a rigger than to invest, as we do
in my firm, in CNC-machining that part into more kindly & effective shape:
http://www.carldouglas.co.uk/downloads/2012riggers.pdf