As to the neckline: I would just leave it alone, no matter if the beard is long or not so long.
As to people laughing or making remarks, I have gotten used to this early on, as already as a kid I was usually almost 1 foot shorter than my classmates. So imagine a group of teenage boys walking past, and one is 1 foot shorter - that does look funny or even ridiculous to some. At some point, this stopped to bother me, and even amused me sometimes. When I grew up (well, at least a bit), the height difference reduced to about 2/3 ft, still quite noticeable. Add the beard to this, and the effect is that I am always noticed, and people remember me because I stand out (well, or rather the opposite?).

crscm