I never got past the part about the neighbors memorializing the suicide of the family member.
That's usually done for someone who died honorably, like in war or line of duty.
When I lived out in Gig Harbor a family lost their son, don't know the details, but they started a 'memorial' facing 14th/Reid Road to his memory. It's been under construction for YEARS and in my opinion is an eyesore. I want to ask them, "Would your son think all this is honoring his memory, or do you think perhaps he'd rather you have dedicated the time and money to something more worthwhile?"
EDIT to add: I don't know if this link will work, but if it does you can switch between the overhead and street view. It looks like he got a lot more done since the last time I drove by there.
His Keep
As to the OP's problem (the memorial, not the confusing paragraph), I second the opinions already stated-
Don't stress over it- you're selling the land
Hope it goes away (and if the neighbor holds to their current property care regime, it may well get so overgrown you can no longer see it. Help that along with some midnight fertilizing)
Talk to the neighbor
Move the driveway to where the memorial cannot be seen