A couple of folks were asking about how to stretch boy like crazy and rack up the points so I thought I'd detail my two main methods for this real quickly in case any other CAGs want to help get to Mars.

The Auto Method

This was actually discovered by someone over at GameFAQs so I can't take credit for it. Make sure the controller auto-off function is disabled, PS2 sleep mode is disabled and your controller is plugged in via USB. What you want to do first, and this is important, is find a level without a lot of moving objects. Keep regenerating repeatedly until you find a calm level. Mushrooms, tops, robots, cars, Katamari, etc. are all your enemy. You don't want anything in the level to be smashing into you and breaking the stretch.

Once you have a good level generated pick a spot near the house. Get some packing tape and tape down the L2 and R2 buttons. Once they're taped, press in and hold down the right analog stick. If your legs are spaced correctly then the game should make you snap in and out of shape repeatedly, driving your length up like crazy. I leave my controller propped up against some scrap wood with a heavy book on top. Make sure you go into your house every other day or so to store all of that length if you don't want to report it all at once. This method nets me roughly 860KM per day.

The 2-piece method

Ok, this will get you length much faster but it is tiresome. Find a big (this is important) and relatively calm level. Stretch BOYy as far as possible off the ends and then let him drop off the edges until he snaps. When you respawn on top of the level, just keep flying up and dropping down OR flying up and bunching up in the air. Every time the two halves of BOY expand or contract in this you will gain length. Once you get the hang of this you will be able to gain well over 50KM per hour but you will wear down your shoulder buttons pretty quickly.

Hope this helps us get to Mars quicker.