When you add that: "The downpayment and closing costs would be one large hurdle"; I can't tell if you can only afford to do this once (thus tying up whatever you have saved) or multiple times.  

Don't split the work between multiple contractors if possible, finding one to do all or most of the work will keep prices down.Challenges were finding replacement pieces for certain items as manufactured homes were very different than stick built as well as going through state guidelines for affixing the house to the land

However, i would like a person with multiple rentals to help guide me to avoid some simple mistakes.

Call every local investor agenda (look at the agents that have investment property listings and call them) and call every local landlord that owns multiple properties (you can get lists off of Deal Machine).

I am in multiple markets and see this as a societal trend.

new houses are getting sold for 600K, old houses switched to multiple offer selling model, just like some places in GTA.

Make sure to vet and look into multiple different PM's per city.

I heard about bigger pockets from a friend of mine that has successfully built and rented multiple properties in our area. 

these can produce good returns but best chance for success is for those that have experience in this area (I am a partner on an effort adding 8 ADUs, but it is not performing to the initial underwriting (underperforming) and it is an experienced team).good luck I get it, but not everyone has the opportunity of scale and building multiple units.

You can have an email for each account and you should be able to set your phone up see multiple accounts at once should you get inquiries or messages.Just log into each account to make updates and price changes.