I think 3 rookies on the ruck line is really pushing it, but I'm pretty sold on going Gawn plus two more.
As much as we know Gawn will drop in price, having those 150s as your C in the first few weeks when he monsters some weak opposition is just gold. The question now is really which two to put with him: Flynn/Meek, Flynn/Hunter, Meek/Hunter or throw Treacy/Fullerton as an F8/R3 swing set.
If Flynn isn't fit for R1 but is nearly there, I'd still be tempted to start him as my donut to play. That really might be too crazy though.