I'm not in love with the blend of styles here. That said, Fonfara has probably gone as far in boxing as he's going to. Making it to contender status is pretty much the peak for him IMO.
On paper Hunter would seem a good choice but reworking fighters 30 plus fights into their career is precarious.
Won't help, Fonfara's issue is walking around at 200lb then then draining to make LHW and he has a shaky chin.