Would this still be recommended if I planned on investing in different markets? 

I would lean towards recommending that you pursue the deal - plus having the property remain in your family may be a net positive for you and your extended family regardless of the ultimate financial return. 

Any tools, APIs, or approaches you’d recommend?

What i would recommend is joining a REA or other real estate meet-up group where you can connect with other likeminded individuals consistently and share knowledge.

I will have a contractor do most of the work from now on Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

If you’re not already using similar software, I’d highly recommend exploring these options—they can save you a lot of headaches down the road.

what markets do you recommend to look at? 

I recommend you do this annually to adjust for utility increases and other variables.

This would further support the recommendation to negotiate a step-down mortgage structure, such as tiered payments or interest rates, to reconcile the seller's valuation expectations with the practical realities of the park’s financial performance and provide a feasible acquisition pathway.

I would not recommend relying on a HELOC as emergency funds for everyone.