litibu I don't know how big your Lako is but I don't think you need to top
it,especially since it sounds like you are getting (scooping up) all the
roots and dirt at once and leaving the whole root system intact unlike the root system in the photo below:
I never had the luxury of a back hoe. It should be better and much easier. The real secret is WATER IT! Baby-sit it for the next month or so with proper watering's and you will have success.
I usually push the envelop and don't top my field transplants no matter how tall. With that said, there more reasons TO top a tall field transplant
than not.
Some reasons might be that it is to tall and heavy to move it through the yard and out the gate or around other tress, down the highway.
Just lifting it out of the ground can be difficult. It can blow over in the
wind easier if it is not topped and some people use the tops for propagation.
The leaves will tell you how the boo feels. I expect It will curl leaves,
then wilt, then drop some weather or not it is In full shade or full sun it
won't matter in the long run. Don't be alarmed as this is just a temporary
set back and it will put out new leaves on the same twigs within weeks.
Sometimes I have had 100% leaf drop on large field transplants and within days if you look very closely you will see little leafs starting to sprout on the branches just like it is spring time. Within a month it will look normal again full of leafs. A minor set back with no lingering effects.
Topping the boo dose have a lingering effect that is visual. "Hey Mike what happened to your bamboo, where are the tops?"
i could be wrong here, but just thinking out loud, It is It is my guess
that boo is self regulating and will top itself it if wants to be topped.
starting with leaf curl, wilt, leaf drop to conserve water then starting at
he top of the culm, will die section by section shutting down what it cant support.
Your Lako will probably be very bottom heavy and won't blow over but better to be safe than sorry, I like Roys method of bracing a boo.
One last thing. I suppose you know not to lay your Lako down on the ground in the sun. That will spell 100% leaf drop, might set it back even more or kill it. If you must lay it down, lay it in the shade and cover it with a wet canvas drop cloth or similar cotton covering from roots to leaf tops and never let it dry out while laying down.
Also never try to grow your bamboo from the back of a truck, its better in the ground: (see photo below by Chuck Theroux)
What progress it has made. Must of had some nice roots.