You are correct - no need for a DBR at every "turning point." (You'd have quite a few if it was required) However, I believe you still need to follow normal Saddlesore rules, so you need a DBR every 300 miles.
I did my 48/10 in September 2017. To make sure I hit every state properly, I used a recipe card with each state's name, and in order of stops in a small box. Each receipt was paper clipped to the appropriate state's card.