This area has an expensive sauna and gym equipment so the owner wanted an additional smart lock installed. 

Have you had any negatives from renting out portable storage containers?

I grew up in a home with a portable dishwasher.

They get full use.We also have a portable Bissell that people can use to clean up messes and they do.

While living in the smaller house I could improve the area around it like build a nice deck for a view, maybe a sauna, firepit etc. 

Consider Temporary Repairs (If Possible)Why: A prolonged lack of a shower may violate “warranty of habitability” laws in your state, which could lead to tenant lawsuits or lease breaks.How:Ask your plumber if a temporary fix (like sealing pipes or installing a portable shower) is possible while waiting on insurance.Keep thorough documentation and save receipts.

luxury cabin, 3100', 4/3/1, nice finishes including spa and sauna, in high fire risk area with total property value ~$500k with CA FAIR was just over $5K fire only. 

Install a sauna or a game room.

However, if you can enhance privacy and add standout features—like a hot tub or a sauna barrel—it could justify higher rates and improve guest experience.

I live in SW Montana where there is a strong STR market and am considering buying a lot locally (2.5 acre overlooking the river/valley/mountains) where I could set up 2-4 Tipi's and rent portable bathroom/washing station for the lot.