Are POE and LPOE Singular or Plural?

Are these terms singular or plural?

Ports of Entry (POE) Land Ports of Entry (LPOE)

Example:

Currently, there are a total of 167 land ports of entry stationed along the borders of Canada and Mexico.

-or-

Currently, there are a total of 167 land ports of entries stationed along the borders of Canada and Mexico.

Solution 1:

They are plural, but if you expand the acronyms, only "port" should be pluralized, thus the correct version is

Currently, there are a total of 167 land ports of entry stationed along the borders of Canada and Mexico.

This is because you are really referring to ports here. "Of entry" merely describes the port, thus it always remains singular.