I would try what I have with the red filter holder to see if it works for me but the project of building a base/work bench for the enlarger is taking longer than expected and I need to mail order almost everything. Thank you for the excellent advice.
Part of the below the lens technique involves constantly moving the filter to avoid projection of any gross defects, in the same way one moves a dodge or burn tool. In theory at least
"There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).