The colonoscopy procedure is no problem...I was knocked out and don’t remember a thing. However the “prep” the day before is nasty, but if you go on a clear liquid diet for a day before the cleanout it is not so bad.. I also have had a barium enema to visualize parts of my colon that could not be scoped. You check your dignity at the door for that procedure.
Have not had one yet, but it seems like you could wind down your food intake over a couple days ahead of time to keep it from being so bad. Eat high fiber for a couple days, then the clear liquid day?