Thanks everyone for chiming in. @Chris Rossi and @Stevie Boy As I said earlier in my OP, my friend tends to wheelie a lot through his turns. Below is a pic of him mid turn on his Senate. See how far back on his ski the water's breaking? I realuze that could just be poor technique/body positioning but wouldn't moving the bindings back further on his ski excentuate that tendency? Maybe I'm not fully understanding how things really work but moving the boots back seems counter-intuitive to me. It seems to me that moving the bindings rearward would make the tail ride even deeper in the water and that would in turn make you have to push harder to smear the tail and get the ski through the turn.
I know for myself, when I went from an old 65" HO Mach 1 that I had outgrown to a 67" Monza (HUGE step up in performance), I couldn't turn the Monza at all the first few runs. I couldn't believe how hard it was to turn that ski. I ended up incrementally moving the bindings about as far forward as I could and that made a HUGE difference. (Don't recall if I did anything with the fin.) Thereafter, the Monza handled like a F1 race car. It took very little effort to make it turn while remaining very stable and foregiving and my skiing improved by huge amounts. I probably improved more over the next few years than I did over the previous 15. But this was me on my Monza and not my friend on his Senate. We have different skiing styles (I'm probably more forward on my ski and more transitional and carving in my turns whereas my friend's turns are more abrupt and jarring) so I'm not sure how much of my experience would apply here.
So getting back to my friend, if you're saying we should try moving the boot back a little on his Senate to make it turn with less effort I will suggest he try that but I'm just not understanding why that should work and it would go against my perhaps misguided instinct to move the bindings forward to get the tip down, make the ski ride a little flatter and make the tail run a little shallower so it takes less backfoot pressure to make it smear through the turn. Am I way off here? Can you walk me through it a bit from your much more knowledgeable point of view to help me understand where you're coming from on the moving the bindings rearward is likely to make the ski turn easier? I appreciate having the chance to learn from someone such as yourselves.