I believe it is completely reasonable to have a clause in your lease that places a cap on utilities with any overage (proven by a bill) being the responsibility of the resident.Our clause states that any electrical bill (we don't have gas, and water has never been a problem) that is over double the same month's bill from last year will have the overage assigned as a fee.It is important to keep your bookkeeping straight if you do assess a fee.

It sounds like you've absorbed a bunch of problems already and a new sewer line and the current basement situation will cost you way less than the $50K in fees to sell it. 

Be prepared to come in with additional cash to close due the the appraisal.   

Here is a list of why adding a single ADU in single family zoned areas in my CA market is typically a poor RE investment:1) The value added by the ADU addition is often significantly less than the cost of adding the ADU.

The referral fees, which operate similar to a multi-level marketing models, often incent these students to post the rare assignment fee check that does get done to every social platform they can and make it seem like they have an "in' with the guru leading the program. 

The terms for a 2nd position loan on a rental is 6%, 25 year term,  and 2 points origination fee.  

I think they all have fees associated with the account if it doesn't meet the threshold.  

That's the other challenge that i've learned, with only one month as SD, if the tenant leaves even in a relatively new build the fees add up. 

The highest fee I've seen for assisting with tenant placement is 10% of one month's rent.

Given that you're not married, that adds some additional complexity.