Increase parameter allowable text length

I have dozens of customer DB's (mySQL in my case) that use the exact same table schema's. I create complex SQL statements and then let PowerBI retrieve the data for customer A in a table. Then I do it again for customer B DB and table, and so on. Then come the day I need to modify the SQL to get another field or change the where clause, etc. I have to update the query one at a time. Based on length of refresh, it can take over an hour. Aha!... let's just make the sql string a parameter and every customer can use the same parameter. If we change the value fo the parameter, they all will start using the modified query. Brilliant! Alas, the parameter Text type only takes ~64 characters. Can we up it to something like 1024 so we can use longer sql statements? Thanks!