Will your provider allow BGP announcements of other IP space?

Depending on how many exits we're talking about I (BrassHornCommunications / AS28715) will happily 'loan' you a /24 and a /48-/36 to route from which will remove the abuse complaints from your provider.

(FWIW I'd rather not give up a /24 if you're happy using your providers v4 for general Tor routing and AS28715's IPv6 for exiting that'd be ideal).

Alternatively I can sponsor your RIPE v6 PI application (subject to the new rules about having a 'contractual relationship yadda yadda) if you'd like to do that.