Carefully trim the hair around his tush with blunt tipped scissors or hair clippers. That'll help with dingleberries
There are dog bath cloths sold just like baby wipes. I don't know that they're better, but they are available.
When I clean the rears of my 2 between baths, I use a warm washcloth with a LITTLE baby shampoo on it. Then I use another wet cloth to "rinse".
I hope this helps. I went thru a really tough time with Rebel when he was a baby. His hair was so thick around his rear when I first got him that a stool hardened half in and half out.
I had to soak his little behind in warm water to get it soft enough to remove, then trim him up.