Originally Posted by
geo8rge
Beat me to it on the fenders.
Pletscher makes/made a rack for the Raleigh Twenty, it is a Model C. I would also check for suppliers that sell to the Dutch or Danish market, I have seen plenty of 20" wheeled bikes with racks on them that the children ride. You could possibly use a seatpost mounted rack, but it will limit your weight carrying abilities and may get in the way when folding.
BTW here is a
direct link to the fenders that will fit. They come in any color you want...as long as it is black.
UPDATE: ThorUSA has a rack listed for 20" wheeled bikes

Look towards the bottom of the page. He also lists SKS fenders for the 20" wheeled bikes.
Aaron