Would we be responsible for any/all freezing that occurs within the ground, but they're responsible for anything above ground to their trailer?

Long story short... our tenant has been in his unit for approximately four months and has reported a greywater backup every month in the septic system (while running laundry, backup occurs in bathtub).We've spent over $6,000 for the sewage company to bring cameras out (4x) and clear clogs. 

I'd love to, but I'm concerned about liability in case of accidents.

Consider when the next recession occurs, where will your tenants get jobs? 

I was in a horrible motorcycle accident on 10/26, before that I  had put together a portfolio of 20 units.

"They" are not giving you the best advice, but it that's the framework supporting your Asset Protection strategy then consider this; if you're worth less than a $1M and a worse case scenario occurs then you're proabably OK if you have a good umbrella policy. 

When the financial crisis occurred, not only did property values plummet, but the rental market crashed as well.

Depending on how many years ago the revaluation occurred may give you a hint of perceived valuation, but it's not a current valuation/appraisal. 

LLC meeting minute with dates etc,  Undercapitalization occurs when a company does not have sufficient capital to conduct normal business operations and pay, or not enough cash flow, unable to access forms of financing its change of bankruptcy is high by not servicing debts etc. 

For naturally occuring rehabs/updates I expense out the materials through the real estate buisness and take no wage.