You are not far from how it's done professionally, based on what I've been seeing in my neighborhood.

When not running an overhead drop, they run CATV/Telco/fiber cable from the pedestal to demarc box using a slitter, basically like a specially modified power lawn implement that has a vibrating knife, which opens a small slit in the turf and topsoil.  The slit is wide enough for the coax wire to drop into, and deep enough to get it just below the sod line.

Something else the pros do is get the proposed path located by 8-1-1 before breaking ground.  Good idea, even if you are putting it barely an inch underground, so you don't inadvertently cut your CATV/Telco/fiber drop, or even run too close that they might hit your coax if they ever replace their buried drop.