change from DDS to DDL

One of the things holding us back from the move to DDL is our current process (homegrown) for making changes to physical files/tables. We have had a utility we have used for years where we enter the name and library of a file we want to change, we change the DDS associated with that file, then after our nightly backup when we know for sure no one is using the file, we do a CHGPF command for every record in the file. Since we have a standard that we never use a physical file in an application and we never use logical files that include all fields by default, this process works very well.

Were we currently use DDL to create tables we use the Navigator GUI to define the table and make changes. That requires an exclusive lock on the table and so it means we have to be here at a time when the file is not in use. Usually very late night or very early morning. The only way I can think of to replicate our nightly process that does the CHGPF is to create an SQL script source file with all the SQL commands needed (which sometimes can be 4-5 commands just to add a field to a table) and then instead of executing CHGPF we do a RUNSQLSTM? And the second part is the DDS has been a good way to document when the layout of the file is and in DDS world you are forced to change the documentation before the change is implemented. What would be the best way to document the new table layout after executing the RUNSQLSTM? My thoughts were to use DSPFFD to an output file. Is there an SQL command that can be used to generate all the SQL commands needed to recreate a table if that were ever to be needed?