You won't have a levelled bed from aligning the bed only in x-direction.
Usually you adjust the two z-steppers once and when you've done a good job with tuning the whole printer, you rarely have to do it again.
A second z-endstop only adds another source of inaccuracy. Because they have their inbuilt repeatability-limit.
If you still want to go that way, search for
dual z-endstops and see how you can do it with marlin.
