At a real keyboard now. The attachment uploader isn't working for some reason. I think that I have a picture of the static, retrievable block technique. Maybe later.
Let's say you have to lower 5 limbs large enough to require a lower device or trunk wrap from 40'. I like the BMS belay spool, and don't have a mini-porty. The BS will/ should release if you use the static, removable technique described in Art and Science of Practical Rigging.
Lower the first piece attached to the end of the rope, using up 40'. Land the piece and the rope will be slack.
Attach the second piece with a sling and carabiner at the 45' mark on the rope (this will be at your position), using the 45'-90' section of the rope. Land the piece. Rope is slack.
Attach the third piece at the 100' mark, lowering until the 140' mark. Land the piece. Rope is slack.
Attach the 4th limb at 145' along the rope, lower out until you have 10' of tail. Land the piece. Rope is slack.
Now, for the 5th piece, advance the extra tail through the BS and tie the last limb to lower the other direction. Cut and lower 5' or so until the rope is tight against the weight of the 4th piece.
Descend. Untie pieces 1-4. You now have 190' of lowering line to drop limb 5 the remaining 35' to the ground.
Having used the static, removable technique that is described in ASPR for remotely hanging a block without quadrupling the force, but having used a BS instead, you can retrieve you lowering device from the ground after lowering your last piece.
As I think about this more...all of this would be having no doubling of force of a block up top and Lowering Device down low. This would only have the force of the weight of the limb (if not shock loading).
A port-a-wrap will not easily remotely release using the static, removable technique because of the cleats/ posts.
Alternatively, you can anchor a second rope at the ground (call this the LD line, in contrast to the lowering line). Take the LD line up the tree with you to the rigging position. Put the LD line through a crotch to redirect it, then anchor the LD on the "far" side of the crotch. Use your lowering line in the LD.
(If using a porty, you will need to change the direction in which the rope feeds so that it is normally operated for limb 5 if you are in a situation where you will run out of line before the last piece is landed. The BS is symmetrical, so it doesn't need to have the lowering line resituated.)
Descend.
If you don't want to carry the LD down the tree...
If you are not having the limb 5 scenario where you will lower the last piece and have both end on the ground, but rather only have the four limbs, your lowering line 'tail' will be off the ground from lowering limb 4. I would secure it to the lowering device after landing limb 4. This allows you to use your lowering line to pull your LD line down through the crotch after untying the LD line from the ground anchor.
