Best way to input data for large catalog??

I am working on a project that is a 80ish page sire directory catalog that we put out yearly. We have always hired this job out but my boss has now decided that we can give it a go in-house. We put out the much smaller (tri-fold) spring update relatively easy but are having problems finding the best way to input all of our data into the larger catalog.

Listings in the catalog will be broken down and categorized by breed and then specific details for each bull displayed within that. I can link to this years catalog as an example if that will help.

I quickly discovered that a simple data merge was not going to suffice for something of this complexity. I did some research and decided to switch to XML but am finding that it has it’s downfalls as well. Every time I want to make a change, I have to clear out my spreadsheet map, edit the .xsm, reload into excel, and remap all avenues. This is not a practical process. I am beginning to think that a plugin is more the way to go but am not sure if I can make a case for the funding side of that.

Is there a way to backdoor this that I am missing? Appreciate any thoughts. Thanks!