I would talk to the neighbors with wells first, and while asking them about their wells, look at their installation AND ask about their experience with the HOA.

Some HOA boards are, ummmh, really strict and impossible to work with, others, like my present HOA board, are very reasonable and willing to consider unusual requests. You need to know which type you are dealing with before you go forward.

I would not consider a pump a "decoration," but who knows how your Board thinks. Also, I think you are right about putting more or less out of sight near or among other utility equipment. Putting in the middle of the front lawn would probably cause some problems with the Board. . .and maybe the neighbors. . .