I think that you would be just fine using the copper. As for cleaning it. You should be cleaning it before every use anyway. I have a lot of copper in my system, and I will be honest. I like being lazy. So cleaning has to be simple or I will not do it. A little star san goes a long way. It really is no different for stainless guys. If you don't want to use star san, then water and vinegar will do the job in minutes. Besides I think a false bottom out of copper would look awesome and if you gave it some dome, supporting your grain weight would be no problem. For all of you nay sayers out there, there are plenty of breweries that use cast iron mash tuns and boil kettles in europe. Most would agree that copper is better than straight up iron. I would also bet that most people would give a dozen reasons why another material is better. If you can make good beer with a copper bottom, and you like it, then why not? That is my two cents.