You have to put your foot down. No permission to buy an enlarger is a no-go. Get some polysulfide toner and tell her that the smell would not occur if you just had an enlarger! Of course, there is a danger that she will get her stuff an leave you, in which case, you don't need to ask anybody for permission anymore, and you get a lot more room for the enlarger.
Paul Bishop used their kitchen as a darkroom after breakfast. He wrote his kitchen off on his taxes as a business expense. This should allow you the extra cash to buy your bride any bauble that is needed to convince her of the merit of your ways.
In the absence of polysulfide toner, put half a dozen eggs under the bathroom cabinet and forget them for six months. After breaking a couple, convince her that enlarger light will cancel out that smell. But, as Ralph sez, the polysulfide toner is quicker; besides rotten eggs don't give your prints that nice color.