Hello Jmaixner and a great big "welcome"! This is soo ironic, I also have a 2001 KIWI 23B (that I havent had for too long), I also upgraded from a 1995 popup. Finally, I also live in a STL suburb.
--best news for you-I work at a local RV dealer (I wont mention which one-you will need to PM me for that info) but you see the infomercials on TV every saturday. And it is not too far from you.
--anyway, we sell the clamps you are looking for. They are on the shelf in stock. As well as just about anything else you would need.
I started with nothing, and still have most of it left
2001 Jayco KIWI 23B
2003 Jeep Grand Cherokee 4.7 AWD