it is really slippery without fins so you must use the edges to cut, to ride perpendicular(not horizontal...you're thinking of the horizontal bop...entirely different)bend your knees a little, just lift with your toes and push with your heels to keep the front edge up but not so much that you slip to your butt(you're just over doing it)...you can ride with your back to the boat perpendicular the same way just press with your toes, keep your head up and look to the back and press with your toes and you'll be backwards perp to the boat....this will teach some handle passing too and then you can do surface 360s... it's funny because im a barefooter we are always turning so when i ride a board this is exactly how i ride it no fins perp to the boat either frontwards or backwards, i can go w2w and 180 in the air whatever that is...
barefooters training to turn do this same thing with shoeskis that are only a little bigger than your feet...and we do it at 20-25 mph, then go to shoeskis that are only the size of your feet then to your barefeet...
and make sure your driver is reading the speedo