The amount of red tape they will have to go through to get that approval - not happening.

So if you build a manufactured house and upgrade everything to 2 x 6 exterior, 16" on center, 2 x 4 interior 2x8 subflooringupgraded to Wind Zone III, trailer hitch wheels removed and set as a permanent structure on n a permanent concrete foundation.

I would be interested in portfolio of SFH, multi -units, and mixed-use, and vacant land zoned for multi-family. 

Bathroom will have corner entry shower insert, and a sizeable single sink vanity.2 zone mini splits will handle HVACElectrical will need to be redone 100amp wont cover both and due to the EV charger in garage, electrician says it will be pushing it with split 200 amp panels, possibly necessitating a split 400 amp service.

Get out of your comfort zone.

.- Neighborhoods to Avoid: Are there any areas that I should steer clear of due to high crime rates, low property values, or other red flags?

The problem is you're in a bit of a limbo zone with your capital.$60k is a great start but it's just not enough to be aggressive.Like you said, you can throw that at a downpayment on something.

Anyone have any ideas for great opportunities in the under 100K purchase zone with good ARVs?  

Get out of your comfort zone.

In general ground up ADU additions in SF zoned areas cost significantly more than they will appraise for.