Super mario brothers 2

Generic title since this will be an generic topic.

SMB2 is not a widely hacked game, to say the least. Due to this there are several things that are not know. (Though I must admit that the data crystal page was fully packed with information!)

There for, I'd like to request some help in figuring things out! And in turn, I will of course try to help other people with what I know.

So, to get down to business: I got done with world 1 but from there on out I ran into a bit of an roadblock. Graphics loaded (sprites and layer 1) are handled in two bits per world. Changing what graphics an world uses is quite easy. However, world 2 (and 6(?)) uses quicksand ground.

For those of you who don't know, SMB2 loads ground data type in the level header, and afterwards uses objects to change what ground setting is used. Rather then using objects to render general ground like how games like SMW does it.

The problem I'm facing is that ground data seem to be pre-set for each world. (Shitty level data format GO!) So in world 2 sand ground would be ground type (I'm guessing these values.) 0000 where as quicksand would be 0001, bricks would be on 0100 or something. World 1, on the other hand, had grass under 0000 and sand under 0001 (and does not have quicksand at all.)

This is where the problem comes in, I don't know what in the world data determines this. (I'm quite sure it's not in the level data header, but I could be wrong.) This is a problem when you are in situations such as mine when you want world 2 to be grassland too, and not have sand in at all.

Edit: To clarify further: [Link]
This is an image of world 2 loading the same graphics/tile tables as world 1 and using ground type 0. Clearly it still renders sand ground, which means it's not an graphics/tile table issue.

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The fun has been doubled!