I have a second, small bathroom in my apartment that I mostly light-proofed (still can only use it at night!), and I have processed sheet film in there. I have a small table I set up in the shower, and I use plastic refrigerator trays from Daiso to do the processing. Not great, but cheap and they work OK.
These days I am mostly shooting 35mm and 120 film. My 5D Mk II needs to be sent in for repair as soon as I get back to the US, and I just shipped all my 4x5 equipment back to the US, so all I have right now are 35mm and medium format. This is a good thing as it's given me an opportunity to get my backlog of undeveloped film down from about 150 rolls to less than 20 now.