Addressing the Underside Visual Advice

I replaced front floor pans and strengthened the tunnel , (had a trans explosion once) laying on my back, and on my knees inside the car.
Do it right now while u go it on the rotisserie , u`ll regret it later if u don`t ! I wish I had at least mini tubbed mine while I was building it .
How much could I get away with on mini tub before it got into affecting the interior seat etc. ?