Stay away from Trims!
If you are using SAII there are pots behind the AGC that can be adjusted to help control the affects of your smile. Stay away from the smiley AGC.
If you are using Stretch taps, they have a tendancy to create rolloff at the extreme band edges. Have you looked at your distribution lines spectrum signature, especially after running through an LE or two?
You may opt to let the main line P to V remain a little out of spec to keep your distribution up to par.
If you are using standard clamshell taps, you can control P to V with a little practice on the SAII board. I believe that SA still has tech papers on their web site.
Good Luck