Anyone know of an institution/bank/whatever that lends in WA state willing to do a purchase money second up to a 90% CLTV? 

You could reach out to Kevin Kim at Geraci LLP in CA who's firm does securities and PML law in all states and is intimate with CA, OR, WA, and ID laws as well as corresponding state specific financial institutions governance (in WA it's called DFI or Department of Financial Institutions) and how to navigate their expectations accordingly... 

But those types of numbers are typically in the 'rarified air' of institutional investors that are looking to park $100 million for some low rate of return.  

Just recently the city (rightly) instituted a CAP on vacation rentals.

You're competing against institutional investors (Brett Robinson to name one) that own a ton of them, market them very well and have this stuff down to a science. 

How do I find the list of financial institutions who do assumable loans?

Probably for the better the city recently instituted a CAP on new licenses.

I talk to national firms every day. the sentiment is overbuilt. maybe not for one person building one house but institutions are avoiding it now 

Its tough because my background is biochemistry, where the MBA moves me more in line into a business direction if anything on paper which is valued by most institutions so if I wanted to stay corporate ladder I think it is justified.

Hello Ezequiel, You can't find them because they don't exist here, at least not in an institutional way.