Am I the only one finding the stem "arghu" exceptionally difficult to pronounce (a tonge trill followed by a uvula trill)?
I believe the most common pronunciation of "gh" is a voiced velar fricative, or a voiced uvular fricative. So that might be easier.
According to Wikipedia, the voiced uvular fricative and uvular trill are in free variation in Standard German i.e. both are pronunciations people use for "r".