> Sodium phosphate is no longer recommended as a bowel preparation regimen due to its serious side effects
Essentially, put in the effort and do the liquid bowel prep.
Consider adding flavour drops to your drink, icing it or turn it into a slushie to make it slightly more interesting to drink. The PEG will make the ice crystals slightly more smoother.
Well in my country, it's still wildly used for people without renal issues.