Check the fur along the abdomen - sometimes trimming the fur off the end of the prepuce and for a few inches in front of the genital area will keep the stream pointed away from the dog better than he is managing now.
I've seen some people use leg guards for the front leg coat made of vinyl material
What I've seen people using at dog shows looks like rain pants with an elastic cuff at the bottom by the wrist and suspenders over the shoulders area. Here is one example
Hope this helps you!