Well that is an interesting question. Let's allow for the most basic level of ability during take off. That would be auto pilot.
How far do you think the trees should be cleared for autopilot to be able to effect a successful take off?
With or without auto-takeoff it would differ from plane to plane ... but to keep this thread simple and on track the OP was focused on the B-29 perk ride.
1. Should the B-29 be a practical choice of rides from every airfield on every runway in every direction on every map?
2. On every field but small ones?
3. On all large fields no matter where they are placed without regard?
4. Should crashing them on takeoff (trees or not) be immune from costing us perks?