I installed all the mods according to the mod guide

I set my game resolution equal to my screen resolution at 2560x1440. I started a new game and did not change the resolution at any time.

Everything ran smoothly until I tried to enter Ku'atraa's warehouse the NW Hive area for Mar's mission, the game crashed everytime when I tried.

Any ideas how I can solve this? If there's no solution can I beat the game without finishing this quest and not going into the warehouse?

Such crashes on entering certain areas are apparently a known issue, even without switching the resolution mid-game; no idea how this can be fixed, though, sorry. (You could probably try uninstalling the widescreen mod to see if it's really the culprit, as there could be other reasons for crashing - that's just the most likely one.)

As for the box quest itself: yes, you can finish the game without completing it, but you'll miss a very, very good piece of equipment later on. (It's not unique, but the only other way to get it is only available at the very end of the game.)