There are occasionally opportunities for grandfathering if there is evidence of legally established conversions that were done previously, but no permit records exist to show it was done. 

This gives them significant control and security.Joint Venture Agreement with Personal Guarantee: We establish a Joint Venture (JV) agreement that includes a personal guarantee, providing an additional layer of security for our investors.Memorandum Filing: We file a memorandum in the county where the property is located.

I would say don't be afraid to utilize the equity line again.

If not, consider establishing one for 2022, after learning the rules.

Buying properties in solid and well established locations2.

Additionally:Is there a specific state where it makes more sense to establish the holding company (now that anonymity in states like WY or DE isn’t the focus)?

Like @Bruce Woodruff said you have to establish your goals and "why" REI or homeownership should be in your life.

I think getting really good at one thing, establishing a network within that niche, and being able to analyze deals quickly is the key making things work.

For that time frame it would not make sense to turn it into a STR as there won't be enough time to establish a history to attract good vacationers.

I have recently started utilizing this platform for just that and I've already had some great conversations with people here.