Do you think the written contract should include something about injury?

Keep in mind this is probably advice to follow the lemmings and you will almost certainly waste your time and money pursuing it, but this is what you need to do.First, and most important, consult a personal injury lawyer.  

Then, to add insult to injury, they depreciated the garage value saying it was old and took 25% off the lowest estimate!

Plus there could be a liability issue if there ever were to be a claim resulting in an injury.

@Ryan Fernholz @Thomas HickeyI just got sued( letter from tenant lawyer ) for this same exact problem, tenant attorney letter claim handrail was broken and stairs slope too steep...cause multiple injuries including fracture to arm. 

I actually spent some time at UWM, and my sister graduated from Marquette, so I'm somewhat familiar with your neck of the woods.

I've been operating my business from Europe for a few years because my son has been getting intensive therapy here for some injuries he sustained at birth.  

Personal Liability: For claims due to Bodily Injury or Property Damage that you becomeLiable for and which is covered under the policy.

Welcome @Andy Beis,I have lots of family over in your neck of the woods in West Plains.  

Umbrellas are typically bodily injury and property damage oriented and don't cover the professional liability that comes with being a landlord.