From what I've seen you serve notice and they have 10 days from when the letter is postmarked to reply. 

Yes, you 100% should serve her with proper notice. 

I own two MHPs in a strong northeast market.57% (in terms of # of units) collected on or before the first97% by the 7th100% by the 15th (always a few stragglers)Roughly 60% pay online/PayNearMe, the rest mail checks.My sample size is too small.

Under the federal moratorium can I still issue them a 30 day notice or do I need to wait until the federal moratorium expired in June 30 before I can do serve them any notice? 

healthy sized sale price, New top price for the area Lessons learned?

The other portion of your question and getting down to the tax benefits of it are going to be best addressed by a CPA yes, as you're going to be going off of a % base or SqFt base and it sounds like it isn't a true 'duplex' equal down the middle in terms of sizing- to then split your deductions 50% down the middle would fall into the real of we don't go there and mess with Uncle Sam that way and stay out of trouble.

Goal is to slowly scale into medium-sized multi-family apartments. 

The administration announced doubling the size of the IRS over ten years.

This was a first come first serve deal, sourced from New Western Acquisitions.

The propery is a good fit for us size and location wise, no rush to move out.