The flaring does me nothing as I use a progressive (550b).
I actually don't secure my press and use two hands on it when pulling the lever also. I haven't finalized my bench yet nor have I made my final move. Hopefully that will all change in the next year or so.
Make it easy on yourself. Bolt your press to a piece of wood. Get a couple of c-clamps and clamp that baby down. Easy on-easy off. And you can move it around on the bench.
My press is bolted, but I c-clamp my powder thrower because I like to put it away in a drawer when done. And sometimes have it in a different spot on the bench.