The only two preamps I can suggest are an Antennas Direct CPA-19 and a Winegard HDP-269. The CPA-19 has a slight edge in noise performance. Both can take higher signal levels better than most other preamps.
But, yes, you're close to overloading if you turn the same antenna & preamp toward Sutro.
If you try it, only to find the amplifier overloads when force fed 16+ powerful signals, are you willing to install a fixed aim antenna dedicated to Sutro... leaving the rotating combo to chase down everything else? An RCA ANT-751 would be plenty of antenna if fixed on Sutro... A Winegard HD7694P would be a 'Premium' option in that roll. Use an A/B switch or auxiliary tuner to choose between the two feeds.
http://forum.tvfool.com/showthread.php?t=2882