for the most part the rule is uninforced and if your PH knows and approves your 358 STA or .358 Norma or even the .338 Win Mag you can use it.....but you will need his approval in advance.
In all sincerity now.....the trip for DG is well over $10,000 and depending on what the game is it's over $30,000 and if one can afford the trip then it seems one can afford a grand for a .375 H&H or bigger gun.