Paul,
W2 yourself does not eliminate the problem suffered by Self-Employed individuals. As a RE for more than 15 years I can assure you any credible lender will still require to see the 1040's and see the adjusted gross income. If you write off alot of items you can still have a negative adjusted gross, thus W2 is far from a solution.

Also, how do you know she will be at 70% LTV? What lender do you know will use the appraised value instead of the purchase price? Only time I have seen this done in 15 years is when the house appraises for LESS than the purchase price, NOT more.