Been playing long time. Not a coach so this is just my opinion.
To me, the common sense approach would be to have them play left handed for serve/FH and hit a 2 HBH. Lefty serve is huge advantage on ad side, and also much easier for lefty to hit righty BH when serving to either court. Ambidextrous player should have ability to develop good 2 HBH. And, lefty forehand CC goes into right handed opponent backhand.
I don't think I would go 2 hands on both sides. Yes, it has worked in the past - see Pancho Segura and Gene Mayer - but reach could be a problem.
This seems like the pragmatic approach as there are several advantages to be left handed in tennis. By the way, my approach seems to have worked pretty well for Rafa Nadal as he is a natural righty.