I always start from the point where the rough mix is at. I never start from zero. Part of what made them fall in love with the song is the vibe they are currently hearing. Part of that vibe is the rough mix. Usually mixing is really about making things sound better from where it is.
I don’t have a Voice Of God alternative. I just use the Voice Of God.
Brainworx‘ „bx_subfilter“ does the trick and it‘s free. Unfiltered Audios „Bass-Mint“ does it too (resonate mode) and is more versatile.
You can also use a parametric eq: Set a high pass filter (low cut) with 24db/oct. If you now crank the Q over 1 you create and start boosting the resonance. Rule of thumb: A Q of 2,5 equals round about a boost of 5 db. Now choose the frequency you want to boost.