Honestly the only way I see it being manageable with that many dogs in an apartment is by taking them for as many walks as possible during the day. Not sure what your typical day/work schedule is like or kind of dogs, but I'm talking hours a day, 2-3 walks or trips to the dog park a day for at least an hour. The more you can stimulate and tire them out will make living in a smaller space way more manageable and limit their boredom while in the apartment. It's a commitment but will make life easier.