After a bit of consideration and lack of proper input about the length of Mission 1; I've decided to incorporate a crescendo event and a more popular section of the franchise - WoodSide Apartment Complex.
At first it was just an extremely tiny house that you ran through, but now it's a full fledged complex - and will feature the same actions found in Silent Hill 2. In order to proceed through to the other side of the building you'll need to get a heavy object (6 pack of pop - same as in SH2 :P) and drop it down the garbage chute.
I figure this should add another at least 5 minutes into the original gameplay, and it might be a good or bad thing. Who knows, I'll have to test it out before I decide to make another drastic change and see if I want to keep this 5 missions or drop it to 3 "longer" sized campaigns.
I'd post a comparison image showing the size difference, but all you really need to know is that it was about a 1/3rd of a 1024 block - and now it's about 3/4's of the block, going through the entire block.