Have you considered a dog-sitter? We live in an apartment with a vlcak (7 year old) and when we need to leave her on her own for more than 5 hours, I make an arrangement for somebody to come and spend 1-3 hrs with her, depending on the situation and length of my absence. I used to hire a translator who came and worked at my place while I was out and additionally could make some extra money. Now a 15 year old neighbor's daughter, who earns a nice addition to her pocket money comes from time to time. Alternatively we have a group of vlcak owners and sometimes help each other in emergency. It's enough for the person just to stay with the vlcak, there is no need to entertain her or take out to make her happy. I'm lucky because such situations are rare, once every few weeks/months, but over the last 7 years there were periods when my husband travelled and I worked longer hours and this solution worked very well.
I don't agree with the thesis, that a vlcak must have access to the garden, imo what he needs most is the company and plenty of exercise and mental stimula.
We take Lorka for really long walks 2-3 times a week, also to play with other dogs, including vlcaks, in fact her social life is richer than ours
We also practise tracking/trailing which makes her tired, happy and let her feel handy.