Get the old-fashioned colonoscopy.
Over the years, I've had four, and they've gotten progressively easier to tolerate.
First one found no polyps. Second one found a bunch. Third one three years later (because of the multiple polyps) showed none. Last one about a year ago showed two. If not for the 'scope, I have no doubt that I'd be a cancer statistic of some description -- survivor, current patient, or dead.
Yes, the hardest part is the afternoon and evening before the procedure. Even that doesn't last as long as it used to. And just get your mind around not getting much sleep because of the second dose in the wee hours — it’s not a huge sacrifice.
Even the SuPrep has gotten (slightly) less vile and much lower in volume. When I first had it, it was all I could do to gag down about a half-gallon of the devil's drink. Thought I was going to throw it all back up and have to start again. Luckily, that didn't happen.
This last time, the volume is down to a pint or so for each of the two doses, and the taste isn't quite as bad. Still not something you'd drink voluntarily, but it's definitely improved.
The procedure itself is mildly embarrassing the first time, and becomes a non-event as you have more of them. Side benefit: my doc uses propofol which will give you the best sleep of your life.
99.99% of people (me included) make it far worse in their own minds than it really is. Plus, if you think the 'scope is embarrassing, what-all do you think treatment for colon cancer might involve?
Just do it.