I really like your idea. We use newspaper pots. Start with a seedling in an individual cell tray. Then into a pint jar sized newspaper pot. Put the plant all the way to the bottom. Remove the lower leaves that will end up under the dirt.
Come planting time. We bury the tomatoes deep again using a post hole digger. I leave the top 6 to 8 inches of plant above ground.

All of the underground stem grows roots. The dolemite and Epson salts is a great idea.