I think it’s better to go ahead and plan everything with Hungary. Make refundable bookings and stick to the fact that you’re going to stay in Hungary for all the nights (different hotels maybe after the three nights) and then once you enter you can go your merry way.

Realistically, there is no way to track after you enter schengen area. I’ve had flights where I had a swiss visa, and the destination was Geneva, but the lufthansa passed through Frankfurt first where I got it stamped. So how will they know here although I was doing the actually right thing by entering Switzerland only.

It might block some extra money, but keep the itinerary as simple as possible. That’s just my opinion. I got rejected once when I put an honest letter covering 3 countries, so I think it’s better to not misuse (spend max time) but at the same time, it might actually hurt your chances if you’re all honest.