the answer to your question is no. unfortunately it is impossible to learn to get up/ride/do siQ tRiQs behind a boat w/o a tower. period end of discussion. towers are a must and completely essential.
I learned behind a SN 2001 back in the day on a skurfer! check out pre pop's extra's with murray and the gang throwin it down on skurfers and whatnot behind and old mastercraft direct drive with low pylon.