A Tent Adjacent to a Tent Containing a Corpse

When there are two tents adjacent to each other, and in one of the tents there is a grave, is it permissible for a Cohen to be in the tent adjacent to it, or is it forbidden by the principle of ’lovud’ (connection)?

If the sky can be seen between the tents, is permissible. We do not apply the principle of ’lovud’ in matters of impurity. And if the sky cannot be seen between the tents, it is forbidden, even though the tents are not of the same height.

The Rema wrote in Yoreh Deah, chapter 376, paragraph 4: 'Two roofs that do not touch each other, even though there is less than three handbreadths between them, are not considered connected for impurity, for we do not say lovud to be stringent. And if one was above the other, even though they do not touch, we say: ’lower and cast’, as if they touch.'
And the Bach wrote that even if the difference between the roofs is more than three handbreadths, nevertheless we say 'lower and cast' since there is a roof of a handbreadth's thickness.