In our simulator, we can't feel if the aircraft is speeding up, or slowing down. Because what we have in our bodies; proprioceptors which kicks in when you're tipped back on an unbalanced chair. In real life, pilots feel everything, but for us, simmers, we have this constraint, thus, we have to rely on our trusty airspeed indicator (ASI).
From what I gather you want a fixed speed to approach a moving boat and just oscillate the pitch? If so, I strongly disagree. First thing I do when I am landing on the boat is to pause the game and unmap my pitch axis. This helps me to use only roll and yaw while pitch for speed is strictly applied. Now the real fun part (for me) begins - moving throttles like crazy to keep that bracket centered and on the crotch. With experience (and I own TMWH and flight HOTAS X PS3 which I currently use because of traveling weight) this comes as a second nature. The Lex Talionis's videos are a gold mine when it comes to landing by throttle. Just with one hand you're grabbing the third wire. The pitch for speed hand.
THE PITCH FOR SPEED HAND