it's hard to help you as no one use the same mix of weapons.
you stated where is no cover in the area enclosed by the wood palissade.. i avoid to step in, not because of the cover, but because you won't have anything to shoot but get troubles to find an issue with alien shooting you from both side.
you may have experimented it?
What i do with my troups, is to split in two groups, one to progress strait in the north, again the palissade, and the second to secure the passage, i mean distract (or kill, or stunned) the 2 aliens in the ufo.
on this map, having a good rocket launcher is effective. One shot, one death, don't worry if the rocket explode on a object behind the alien, it works too. If alien get armor, you may add a snipper to finish at long range.
in average, aliens suffer big loss at 3td or 4th turn, but can a alien actually suffer... i wonder.