New wooden utility item: The Shelf!

A new block for every wood type, it would automatically put you into crawl if you walk into the side while crouching. As crawling has now been added to Bedrock edition, it seems there should be a more obvious way to get into crawl rather than using the seemingly unintended trapdoor mechanic?

While a crawl button would make sense (double tapping shift or a new hotkey), I see the drawback of allowing players to crawl at all times (unintended consequences and getting out of bounds on old maps, adventure maps, or prisons). 

The shelf would act as an easy entrance to tunnels and you could walk on top of them as solid blocks. They also make cute tables and have a similar look to scaffolding. Concept art here: https://i.imgur.com/M0jGPMm.png