As I mentioned above the dowel sticks and blackout material have worked well for me for over 35 years. You could also consider the black plastic garden sheeting. I used that in a similar way to black out the two windows in my darkroom. It is pretty heavy and you could use a double layer. The nice thing is it can be placed or removed in a minute and when rolled up on the dowels like a scroll takes up little storage space. Make it long and wide enough to more than cover the door. The sides can be secured with self-stick Velcro.
How about attaching the enlarger to the back of the counter top or to the wall and cutting a square out of the counter top so you can lower the easel to multiple positions for bigger prints? This is featured in examples of home darkrooms shown in the Kodak darkroom construction book.
“You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt