wayneo - no need to worry about giving me credit. I just wanted to be sure you saw that thread, as it had some detailed info. Also, if you or anyone else ends up pursuing this, I certainly would hope you would have a discussion about it here, and especially post a summary if you end up installing one. The Thetford is probably the most talked about appliance in the TM, and lots of people would be interested in your solution - I guarantee it!
I don't know about the drain hole lineup as I didn't get that far -- once I did the math and realized it would be much heavier and use a fair amount fresh water, which is in precious supply with my 20 gal tank, I decided against it.
There have been a number of folks here that have replaced the Thetford with something permanent. They install black tanks underneath, or just use a grey tote on the ground. Someone even just put a rug over the drain hole and put a cassette toilet on top -- honestly, that sounds like the track I might pursue if I ever became further motivated to replace the Thetford.
I use the Thetford for all my waste needs (does that sound a commercial or what?), and after completely removing the vinyl skirt, I'm pretty content with it. Feel free to PM me for details if you don't want to discuss them here.
Dave