This would make only half of the purchase eligible for 1031 treatment.  

While Washington is a super lien state, it seems that there is separate treatment for COA and HOA.Super Lien.

The tax treatment is typically the same. 

A Solo 401k can purchase a rental property and in this case can and should receive the rental income which will have the special tax treatment of the Solo 401k (either tax deferred or tax free depending on the type of 401k funds used for the investment).What cannot happen is a transfer from a disqualified person to the Solo 401k.

That is, she must give her clients (the seller, if she has the listing, or the buyer, if she brings the buyer and represents the buyer rather than the seller) preferential treatment.

Coined the name "Short term rental loophole" which can provide massive tax savings for you, unfortunately the federal tax code establishes stringent criteria, including guest stays limited to seven days on average and the provision of basic hotel-like services, to qualify for this advantageous tax treatment. 

I will have to ask my clients if they got the same treatment.. 

My in-laws did that when they moved from Cupertino to Nevada City... same scenario  sold their little rancher for 1.5 and bought a really nice home in for 600k but the rancher they paid 30k for in the mid 60's  Best tax treatment around Is to Live in Vancouver Washington  work there .. pay no state income tax. property tax's are lower ( but they have a 1.7% sales tax when you eventually sell) then cross the bridge and pay NO sales tax on everything you buy in Oregon.. that's why you have major malls right across the river HUGE costo etc..

Will the treatment keep them away for good?

A REAL General Contractor gets very special treatment and they should, Even at lowly Home Depot every order over $2000 goes back to corporate in Atlanta for review, where they will knock off 5-25%.