You are on the right track, and now is a good time to do it. Bamboo like to be moist, but not in standing water; summer watering will be important. Planting in a mound would be good as it will make it easier to control rhizome growth in future years.

However, I have some suggestions for you. First, I presume you have not dug bamboo before, and you may not realize that it's quite a job. It often is best if two people work on it together. In addition, there are some special techniques required that are different from digging up other plants. I'll email you some written instructions. Secondly, I'm going to discourage you from cutting off the culms. If you take a root ball and don't leave any aboveground growth, it may be a couple of years before the roots produce new culms, and when they do they will be small in height and diameter for a couple more years. If you expect to have a clump of bamboo that begins to resemble the stuff you want to dig up, in less than 5 years, you should leave one or more culms. If you can't transport something that tall, top the culm(s) as little as you can, and no more than half. Good luck.

Kudzu knows what he is talking about. :) If you have a drought, you really need to water them in the summer. I have some boo that has been in the ground for 4 or more years and they all look awful because I didn't water them during the summer, I think that is why they all turned yellow.

I had transplanted some boos and had cut the growing culm off and had a good sized root. But, like he says, it will take years for it to start growing at all.

To get the rhizome out easily, I found that by using pruning shears to cut it is an easier way than trying to hack through it with a spade.