Verified answer

As long as the unit has power and proper ventilation it does not care where it operates. Remember that the unit drips out the back and you will need to provide a way for the water to go where it is not an issue. Depending on model you may need to angle the unit back to help the water have fall.

It will not work if you don't have enough room for air to be pulled in on the sides.

A sleeve A/C pulls and pushes air out the back. A normal window unit pulls air through the sides and out the back.

As long as the sleeve extends out side . You can even drill holes in the side to help the exhaust air . The problem would be restricted exhaust air flow that would lead to compressor burn out .

it won't be as efficient as the air conditioner without the sleeve, but why not try it and see what happens, then make up your mind.

i have seen this done before