hire a "translator" for a day

The local T.I. can probably suggest someone.

Perhaps try the university to see if a student would like to earn some cash.
A translator may cost more than a private guide.

I am thinking you might contact a university, like the Universitaet Hamburg,
https://www.uni-hamburg.de/en/internationales/kontakt.html
Page down and you will see a Translation Coordinator. If I know anything about universities, it is there are always plenty of hungry graduate students that could use the work. Why don't you ask?

Geneological research can be something of a specialty, as records were written in old German script.

This does not really relate to your actual question about a German translator, but there are some resources online to study so that trying to read something like the old church records may be easier for you, particularly if you have a translator who is not familiar with genealogy.

Here are a couple of links on the FamilySearch.org site with a cheat sheet for German Handwriting including the old German gothic script.

https://familysearch.org/wiki/en/Germany_Handwriting

There are also some German genealogy tutorials which may or may not be of interest:

https://familysearch.org/ask/learningViewer/235

If you are looking at old church records you may want to invest in a small handheld scanner to make a copy of the pertinent pages.

I spent some time researching in the Family History Library in SLC last year and was shocked that they had microfilm of the 1680-1750 church records from the small German town my ancestors emigrated from. It may be that your spouse's family church records are housed there as well.

editing to add: Just for fun, did a search on FamilySearch for Fintel, Germany and there are 3 microfilm records held at the Family History Library in SLC for the church records from 1820-1905. As I understand it, any LDS church with a history library (will probably be one of the bigger churches if you have several near you) can order this from SLC for you to view at their library on a microfilm viewer.

https://familysearch.org/search/catalog/24756?availability=Family%20History%20Library

http://www.worldcat.org/title/kirchenbuch-1820-1905/oclc/866668917

(Heiraten = Marriage, Konfirmationen = Confirmation, Taufen = Christening, Tote = Death)

Thanks for the suggestions!

Hello! We did a similar genealogical trip two decembers ago. One thing that really helped us was going to the website for the towns that were were visiting and emailing the general email address from the site asking to be connected with a genealogy person/group in the town. I then set up appointments with each of the people that emailed me back. A few sent info ahead of time. Others, because they had a heads up we were coming, had a lot of material pulled together for us. One place even was able to point us in the direction where my great-great grandfather's sawmill was located and we even got copies of the blueprints to the mill. Another lady had some church records pulled for us. It was cool.

There was one spot that I did not have an appointment, and we decided to wing it. It was terrible. So much got lost in translation and there was so much confusion.

Enjoy your trip!!