Cast iron sewer pipe fittings

I have used a diamond tipped sawzall blade and it worked fine, used water on cut for lubrication. support the horizontal run with wooden blocks or strapping which you'll need for support after fernco couplings. I removed some dirt with a small shovel but my clearance was probably less than yours, like 10 inches or so. Hopefully you don't have to crawl very far to get to this. It is a PIA but Mopar guys are smarter than most. I think I saw some vertical pipe clamps at lowes or home depot if you need those.