I would have personally waited a bit to list in the spring when things are hot and everyone is over-bidding. 

Hey Stuart, the mid-market is a pretty hot and affordable.

You can look at a mobile home and see it as an easy rental with new carpet, trim and some paint but there are other bigger uglier expenses that can come up.Roof Replacement, soft floors (water damage) in kitchens and bathrooms- most floors are particle board, exterior door replacement (special order), underbelly insulation falling, bad hot water tanks with rotten floor underneath (real joy), bad windows (water again), bad bloated siding (water), water damaged base frame around perimeter of home, cracked tubs (special orders) and frozen pipes (Good luck finding a plumber to come work on a mobile home- they do not exist). 

Quick tips…✅ Everyday Homeowners - track all home improvements as you could qualify for energy efficiency home improvement credit - new exterior windows, new central A/C, new hot water heater, new insulation material.✅ Investors - Keep detailed records of ALL rental property expenses to reduce your taxable income - helping your CPA spot additional tax saving opportunities.Imperative to use a CPA who is well versed in Real Estate tax code.My CPA is just that - DM me to get his contact information....

You can afford to pay a bit more if rates cool down.We need to also remember that BRRRR become a really hot topic in a low interest environment.

-My budget is max 250k, so yes I am trying to find a hot market neighborhood that can accommodate these two points. 

You're increasing the need for hot and cold air dramatically and it's doubtful the existing system will be adequate.But, in answer to your original question - yes you will need a permit.

Spokane has been a hot market for investing for awhile and local meetups and Facebook groups will be able to provide you the best information about what's working in your local market as well as any specific market risks / challenges.John

Quote from @Matthew Kwan: For those who are currently shopping or looking for a loan since rate cuts has been a hot topic.

Can I risk building a home at the slot and sell it which will be faster than selling a lot?