How do I 'lock' weighting for a set time period without 1000's of line items over a year.

I work for a large corporate railway and we are planning on using survey data as corporate KPI's published to shareholders/ stakeholders each month / quarter/ FY. As an example, it is critical the results for 'December 2020' in our dashboard do not change once they have been publicly reported. We currently do this by creating an embedded data field called 'Month' and we close the surveys for that 'Month' on Working Day 6 of the next month (etc).
This is fine, however we also need to weight the data based on patronage across our different services (and classes within each service). This is approx. 50 unique combinations per month. We can weight the data each month via this method; but at 50 combinations per month, you can imagine the line items displayed in Qualtrics within Data & Analysis > Weighting > Static Weighting is looking very unwieldy and extremely open to error after only 3 months. We plan on running this for years, so there will be 600 individual lines to update by the end of the year. Is there a simple way to simply upload the weights (calculated in Excel) and append them to the relevant Case ID (i.e. what you can easily do in Excel / SPSS) - and then use this weight in the CX dashboards? Alternatively, are there any simpler ways of doing this as I imagine many other corporate users experience the same issues here.
 
I haven't been able to receive any advice from Support or my Client Support manager, so trying my luck on this forum.