I use the SSP charcoal baskets perpendicular to the charcoal grate, same idea as another grate really. If I'm lighting small pieces to start (end of a bag, all that's on hand at the moment, etc.), occasionally I'll line the inside of the bottom of the SSP charcoal basket with tin foil. It doesn't stop every piece from falling through but it seems to get the majority.
Thinner guage expanded metal can be bent or "molded" with little effort, i.e. find a 1'x1' square of expanded metal and just bend the corners up the side of the bowl.