55 quid? Bloody hell! I actually am learning Spanish, but it's a painfully slow process. And we do have some friends there. I'd move to Granada and eat tapas tomorrow!
The unemployment rates and my communication would be the main barriers. But would she be allowed to live with me in Spain while we were becoming eligible for the Singh Thing?
Yes, she would be able to live with you - in fact, she would have the automatic right to live and work in the UK as the spouse of an EEA citizen living and working in the UK...she would just need an EEA Family Permit for Spain

.
Basically, if EEA citizens (non-British) move to the UK and exercise their EEA Treaty Right by working/studying/being self-sufficient etc., their non-EEA family members are automatically allowed to live and work in the UK with them. Same goes for UK citizens living and working in any other EEA country.
The problem is that a UK citizen living in the UK and wanting to bring their non-EEA spouse to the UK cannot use the EEA route and has to get a spousal visa for them instead (same as for a Spanish citizen wanting to bring their spouse to Spain).
HOWEVER, if they were to move to a different EEA country with their spouse and live and work there together for a decent length of time, integrating their life in that country, they can use the EEA route, under Surinder Singh, to move to the UK.
p.s. ksand, you don't see any flaws in my original America-Spain-London plan either, no?
No, there shouldn't be any issue, as long as you can still meet the income requirement from your earnings over the previous 12 months (and all the other requirements).
The Surinder Singh route, if you can do it, would save you thousands of pounds in UK visa fees though, since the EEA Family Permit is free, then the 5-year EEA Residence Card is currently £55 and the Permanent Residence Card (after 5 years) is also currently £55.
In comparison, the spousal visa is currently £1,556, then the next visa (FLR(M)) is £1,149 and ILR is £1,500... and the fees will only keep rising each year.