One issue you may have to deal with is the line in the lifting capacity charts from Grove. The one that says "Handling of personnel from the boom is not authorized except with equipment furnished and installed by Grove Manufacturing Company. "
Grove isn't going to make you a basket and install it on your crane. Tradesman has a factory basket. I have a National boom truck basket, that fits on my national boom truck, and I made a adapter that makes it fit on my jib of my RT740 Grove, for work that my national won't reach. Its not "authorized" as I have it on my RT. I'm willing to live with that, and stay within my 50% deduct for manbasket work. It may bite me someday if something happens, and I guess that's me sticking my neck out, with making a tool to do a job.
I just wanted you to be aware , of what is in the book and the risks involved. I'm not saying don't make a basket to do the job. But I just want you aware of the "factory" statement on the subject.
And I do understand what you are doing dropping with a line through the ball, I have one current customer that does it like that. I used to do a lot of work with another customer that always worked that way. I thought your concern was cutting off dead pieces and throwing them down.
Sometimes with these we will cut and throw smaller pieces.
Which you can do from a two man hanging basket. If you and your guys aren't comfortable with working that way, by all means use a pin on basket. Most of the time when guys are having trouble working out of the basket, its because of inexperience on the part of the operator or the guys in the tree, or in working together. A guy who doesn't run crane all the time, makes for a miserable day in the basket. He will have the poor guys in the basket swinging all over. Guys in the basket, that try to drag the basket all over in the tree by pulling it around everywhere, can also make it difficult. Usually after everyone gets on the same page with each other, it goes pretty good.
One of my biggest problems with a pin on, is tree trunk or other structures in the way of direct line of sight to the area you need to be placed in. Invariably, there will be more than one large trunk section, and a big leader going directly opposite of the crane out 40' further away, and you can't move the crane out of the driveway to "get around the corner" of the trunk. Cut your way in is the only way then.
The other problem with a pin on basket, is it won't knuckle in on itself like a bucket truck, it starts out at 30' length, and just doesn't get any shorter. Its even worse if you have it pinned on with dead stick out, or a jib on. You can't get any closer than 60' to yourself then. Works fine for 100' up, you just end up getting stuck in on yourself when your 40' off the ground, bringing down the rest of the trunk. Some jobs you may have all the room in the world to work with, and then its not a big deal. Or just pull the crane out of the way and finish with the bucket truck. Those issues are much less if you are just working off powered boom with no dead stick or jib in.
If you want a pin on basket, by all means buy one or build one, I was just trying to be helpful with some of the disadvantages of them, they just don't work in all situations. I really like our pin on basket, and its much nicer for a lot of jobs than a swinging basket, it just won't do every job. I myself, find it easier to place the guys smoothly where they need to be with a hanging basket, than with a pin on basket. Especially at long radius with a lot of boom out.