Hi
I have some gold plated drum hardware. I've never tried to clean my new drum - the LangPercussion......Arnie Lang sent me some care instructions I can dig them out for you later (not onsite right now).
I bought an original Cadillac Green tom a few months ago. A former owner spray painted all the gold hardware. I took a chance buying it and found there indeed was 24K gold under the paint. The g e w e ler told me I could use Acetone to safely remove the paint. I used a soft cloth drenched in Acetone and it worked fine. I also used Dawn Liquid (the blue bottle) soap to clean the parts with good results.....did not see any sign of gold removal.
Gretsch has their gold hardware 'flash-plated' so there is not a lot of gold there......so I'm told. I would think if you're careful you should be alright.
How did the gold plated hoop rust? Gold does not rust.......right? Are you saying the gold has been worn off and in those warn off areas the hoops and rust has set in? If this is the case - and you want to clean the rust off - whatever you use if it gets on the gold it will probably remove some or all of it. If I were you and the rust is not too bad....do like you're thinking of doing and use the mild soap and if you want to clean the rust off - the gold has gone in those areas anyway....just use a rust remover....carefully.
I'm not an expert I'm just saying what I might do in your situation.
Nice drum I bet....