In my market refi appraisals are consistently conservative and come in significantly lower than if there was a full market price offer.  

Yes, you can do HELOC but not want to dive into the nuancesI would rather be Avatar 1 that leverages debt by purchase rentals consistently for low down vs tying up cash into 1 house hack at 20% down.Backing in my answer with actual case studyI recently put together a case study of one our clients that has done this every year consistently since 2016 and is now on his 7 house hack.

If you consistently analyze properties, recognizing a good deal will be much easier when it shows up.

Of course there are exceptions, for example COVID which disrupted the cycle schedule, but most of the time cycles remain pretty consistent.

Zillow consistently shows prices much higher than Redfin, for example. 

As for other potential challenges, keeping the layout consistent and dealing with any uneven subflooring might be things to watch out for.I've had a similar experience with a project like this, and I found that using this comparison site really helped me find affordable service options.

If you consistently analyze properties, recognizing a good deal will be much easier when it shows up.

Be fair and be consistent. 

Rockaway Beach has made consistent appearances on many top beach STR investment lists due to a balanced price to ROI ratio (and majestic destination) with a historically a low barrier to an STR permit.

The mailers I send consist of distressed properties that I drive by using the driving for dollars method, pre-foreclosures, divorces, and absentee owners.