I'm not clear on why you want a container if the tree is growing in the ground. Trees that are grown in buried nursery containers with holes at sides and bottom will often survive for long periods because the roots run through the drain holes in search of water & nutrients. A tree that is grown above ground and whose roots are allowed to run through the holes in this type of nursery containers also usually do OK. I have seen trees that are 15 years old growing in such a manner. Often the roots split the container & offer even more opportunity for roots to run. Plants grown in containers that have a single drain hole (unless the container splits from root pressure) will grow for a year or two & then begin a steady decline.

If you never want to mess with roots, plant your tree in the ground, or as you suggest, cut the bottom out of the container. Containerized trees, even those that are potted up regularly, will eventually show steady decline in vitality as large roots fill the container, leaving less and less room for the all-important fine feeder roots.

Your crab will likely do fine if you wait until spring (before bud movement, about the time frost is out of the ground) to lift it, remove the container, and plant in an appropriate spot.

Al