> My primary concern about going about it this way is that this would make my fiancee’s debt to income ratio comparatively enormous even though for our combined income we’re buying well below our means.

Her DTI is the same if you’re on the loan when lenders look at her individually, so it doesn’t matter.

> we could refinance in a few years when my credit is improved and the bankruptcy has been removed from my credit report and that would solve it, but my concern is for how this will impact her credit score and what implications it may have to get another loan like a car loan, renovation loan, etc. The lender I spoke to was pretty assertive that this would be a better move for us overall, but I wanted to field some other opinions.

No different than if you are on the loan

The full loan payment, regardless of the number of co-signers, will be used to calculate her DTI for future credit