I'll take any and all advice any of you have, but the two things I'm looking for specifically are: what sites, services, and/or software you use and recommend for sceening and managing tenants? 

I can definitely provide a recommendation.

Anyone you recommend in Minnesota?

I'm a little biased (am the owner) but seriously pumped to see you recommending it.

While outsourcing overseas may be tempting, I would recommend nailing down your processes prior to teaching someone, or you'll wind up with their processes, at best. 

Florida is a unique state for MHP law and the insurance has gotten very expensive there too.I recommend checking out @Frank Rolfe's mobile home university content if you haven't already.

@Serge Hounkponou Recommend you first figure out the property Class you want to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

If you can get financial support to get a duplex/triplex, I would recommend this.

I see you're in the Boston area, so if you're looking for cash flowing markets I'd recommend Lowell, Fitchburg, Leominster, just to name a few.

For flipping I would also normally not recommend adding an ADU.