Extremely large hands are very infrequent. The biggest I have seen was 33 hcp in the 1960s. The auction was 2C-2D-6N justified by “I have 33 points”! The biggest hand I have held was 27 points and partner opened 1C ahead of me so the auction was easy: 1C-7NT. This 29 point monster arrived in the Interstate teams event in Brisbane earlier this year and you might like to think how you would bid it. Bert Forage and Julia Corr reached 7NT where many languished at the six level.
The problem is the type of responses which you might choose to respond to 2C. If 2D, negative or waiting, is bid, it will be difficult. If North responds 3D, South has to bid 4C and, although there will be some anxiety about missing a spade fit, South can probably just jump to 7NT at some stage. If the initial response is a negative 2D, the auction will proceed 2C-2D-3C-3D-3S-3N which is fine except that North has bid like someone with no points.
Perhaps North should bid 4NT rather than 3NT but won’t that be Blackwood for spades? It’s very difficult to recover at that point. So how did Bert and Julia do it? They play control showing responses to 2C and a 2H response showed one ace or two kings and South has no problem at that point and could jump immediately to 7NT. Using that kind of method, one might have an auction like 2C-2H-3C-3D-3S-4C and would know 7NT was really safe. The actual auction at my table was as shown. South is one of the best card players in Australia but has very retro bidding methods: weak 1NT and 4 card majors! Still his partner responded an artificial 2S showing 7-9 points which makes the auction game forcing. Over 2NT, North asked for a 5 card major and then subsided in 3NT having bid all their values. South simply corrected to 7NT. Will your methods bid this or do you need to consult Bert about his methods?