Your story is absolutely amazing! Did your godparents know what your godbrother was up to? I guess he must told his parents where he wanted to go to. I think it is very kind of your parents to let you play in mud like this even that you kids turned out muddier than they probably expected
I grew up with constant reminders to stay clean and to keep out of the puddles and to stay on the dry side of the path and so on. Only as an adult am I now able to play in the rain, the puddles, and the mud and I absolutely love it.
In Sweden is a manufacturer of raingear. I own several jackets and dungarees because they have a high rise and look very child-like. Maybe you have heard of farmerrain.com?
Farm holiday is offered in Germany quite often and I discovered a nice farm a few years ago. The farmer let me get as dirty as I want in whatever mud I want
The PVC raingear rinses off easily which they did when it became necessary (which was about twice a day). They even suggested that I take a swim in a big muddy pond in the woods 
You may have guessed it I'm German and I apologize for my poor English.
Keep on writing!
Boy (clean and dry today)