28% seems excessive...

In the last 12 months, I've earned in excess of $500/hr on BP.

This entire area is riddled with hard water (I have not had it tested, but judging by my research of the area it is in excess of 17 gpg).While I have plumbing experience (gutted and replaced an entire bathroom in my prior residence last year) water softeners are not something I’ve encountered.If anyone has insight into what the major differences between these two units are I would be very thankful for an explanation and recommendation of why I would spend $1,500 more for the second one.$500: 40,200 Grain Water Softener https://www.homedepot.com/p/203219780$2,000: 10 GPM Whole House Water Filtration and NaturSoft Water Softener Alternative System https://www.homedepot.com/p/205423703I believe I understand the installation process and could manage that on my own, but I do want to ensure I’m choosing right the first time I buy.

. - would you be open to sharing the verbiage you include in your lease regarding excess use? 

That is excessive and in the absolute majority of states not operative (didn't check MA for this post). 

Or things like renewal fees or termination fees excess of what I mentioned on tenant leasing.

Once those girls start having babies there is an excess of animals and the price drops.

The following are some property selection guidelines.Older properties require more maintenance than newer properties.Composition roofs require more maintenance than tile roofs.Properties in climates with hard freezes require more maintenance than properties in mild climates.Properties in locations with a lot of moisture require more maintenance than properties in dryer climates.Wood siding requires more maintenance than aluminum or stucco siding.Properties with lush vegetation require more maintenance than properties with little or no vegetation.Locations with high levels of termite activity will require more maintenance than areas with little or no termite activity.The tenant pool has a significant impact on your ongoing maintenance cost.

Because it seems excessive to you doesn't mean it won't hold up in eviction court.This clause doesn't take advantage of anyone and no one is forced to live under these rules.

It gives the potential buyer incentive to exercise their option as early as they can (unless too much of the excess rent is be credited against the down payment and it washes out the SP increases).I am not sure that I would want to charge for an option extension if they are being a good tenant and taking care of my property.