If you have the budget then Latham Island .Tanzania .East Africa should be on your list.
In the mid to late 80's I worked on a charter boat out of Dar Es Salaam and the size of Doggies and Gt's was exceptional, back then the gear was very old school but we still managed Doggies to 98kg and a Gt of 62kg .
I know the Tanzanian Govt opened up their fishery to longliners for the massive schools of big eye and Yellowfin in the region, at the time there was no commercial pressure ,that may have changed now
If your looking for a bit of frontier fishing then the Comores islands would be a great destination .
Regards JJ