Everything can be done. It's just a matter of whether you are willing to invest in it or not. Why don't the two of you do a JV to develop what you need!?
(For instance, I am investing heavily into MW with four developers working full time to implement the roadmap. Initially the development is for supplementing MW. In the longer run MW will become a subsystem.
We have already done a lot of things that "can't" be done and this is possible partially thanks to the very well thought through architecture of MW and the things you mention above is already there but not with WHMCS. Kudos to
@twisted1919 for his awesome work with MW by the way . )
So yes, it can be done! Just do it! Good luck!