Auction.com will be a great resource to find foreclosure auctions.

I would think realtors that are experienced in working with investment buyers would be a great resource but how would I go about finding a good realtor to help me confirm I'm not looking at a property that will be a rental liability?

What resources did you all use to find profitable US locations, beyond AirDna?  

Meetup.com is a good resource for those but some of the groups will also post here on Bigger Pockets Marketplace too.

What resources would you say have been the most helpful for learning how to transition from SFH to larger MFH?

So glad you reached out on BP, it's such a great resource.

Contact your housing authority and see if they can point you to any resources.

It really depends on your goals and resources. 

You can gain a lot of resources that way, as well as potential wholesale buyers.

I've been a member of the tribe for almost a year now and can say it is the single best free resource for MHP investors out there.