I know that I’m probably over thinking things and making them more difficult than needed. But here it is anyway.
Any thoughts on blocking off the downspout so that the sh stays up in the gutter and then vacuuming it out?
Yes, you are.
No, never.
Listen, as best I can tell, the caveman invented the wheel. No need to reinvent it.
But we do have very little runoff nowadays. We catch that in a bag and then flush the SH left standing in the gutter into said bag. If the roof section is small, I just flood the gutter with water and then let it flow a bit afterwards.
Thinking is good. Over thinking can kill a man.
Thats why I like forums, I can think about it a little then post it here to get shot down before I put too much effort into it 
Here’s a little secret “RINSE RINSE RINSE!!” and you will be fine:D
could not have said it better
