If you paid cash for the foreclosure, you can get a construction loan at a local community bank or credit union. 

Is there anything I should focus on for the design / layout if the purpose is mainly for renting out? 

We have been around the bigger pockets community for over a decade now and have more 5 star reviews on bigger pockets than any company on this website in any industry (>270 5 Star reviews).

The risk of "piercing the veil" applies more to LLCs when personal and business finances are not properly separated, not necessarily to individual landlords renting a portion of their home.A more practical approach is ensuring you have a solid lease agreement, sufficient liability insurance (including an umbrella policy), and properly reporting rental income and deductions on your tax return (Schedule E).

My goal is to make this property available to insurance companies, disaster recovery specialists, and individuals displaced by fire, flood, or other catastrophic events.I am seeking guidance on the most effective approach to market this property, specifically:Recommended Insurance and Disaster Recovery ContactsAre there specialized companies that manage temporary housing for insurance claims?

For some reason I am getting you want to approach this from an emotional versus business standpoint.  

Residential property rental: Could this be a scalable and profitable approach, or is it too risky?

Can try to reposition to Class B, but neighborhood may impede these efforts.Vacancy Est: Historically 10%, but 15-20% should be used to also cover tenant nonpayment, eviction costs & damages.Tenant Pool: majority will have FICO scores of 560-620 (approaching 22% probability of default), many blemishes, but should have no evictions in last 2 years.

You could make this work ST, MT or LT, depending on how you approach it - the key with unique grounds is owner-provided upkeep and service built into the listing and what permits allow. 

Welcome Jakob, do you have any specific questions so the community can help