I would have to disagree with that. It is 4 adults or children over 3 years old. Children under 3 don't count, no matter how many of them you have. Many people have twins, triplets or more then one child under the age of 3.
I think you could do a studio this one time, but it would be very tight. Especially if the 3 year old likes to sleep in a pack and play too (ours does.) Our last trip at VB we had both a bed with rails for her and a pack in play. She chose the pack and play every time (and she was 3 years old.) Or if the 3 year old or baby rather sleep with you.
I recomend a inn room at VB ocean view, Sun to Friday. When we were there in May it was 10 points a night, 50 points for the whole trip. 2 full size beds, and room for 2 pack in plays if needed. A great trip and we just love the place.
I would think this is the last year you could manage it, and still pushing it.
I don't think counting a 3 year old for under 3 in a hotel room is the same as trying to sneak them into a theme park for free. (especailly depending on when the 3 years old birthday is, my 3 year old was born in March and is very small for her size.) It also really depends on how comfortable you are as a family being in one room. Some families can do it with no problems, others it is unheard of.