Our motorhome is not as heavy as yours but is over 3500kgs which is, I believe, where weight restrictions for recovery are generally applied (happy to be put right if this is wrong :whistle: ).
We insure through Comfort and have their 365 day European breakdown cover via the RAC, the breakdown scheme is called Horizon Advantage. May be worth you investigating whether they would cover you?
Other than that I believe that
ADAC don't have a weight restriction for motorhomes but again you'd need to check for yourself.
Hope this helps.