Hmmm, I have not tried fitting 3 across in the Pilot, but I have noticed that too many seats tend to sink down into the 40/60 crease over time -- it's important that each carseat is independently secure: must not move more than 1" at the belt path without relying on pressure from adjacent seats.... You might have more luck with the
Sunshine Kids Radian, but I would say you should definitely have your local CPST check 'em out for you

Good luck!