If you don't ask, you don't get. The worst thing that can happen is that they simply say no. If $1000 is too much, maybe they'll donate a smaller amount. I presume they have that option.
If the corporation has an on-line donation request process, then it looks like they're trying to make it easy for Mr. & Ms. Littleperson to request.
So I'd say you are right in-line, and haven't overstepped anything.
After having to volunteer last year because I couldn't raise the money (this is my 5th year participating) I am hell bent and determined to cross that finishing line.
Crossing it three years in a row and having to watch from the sidelines was not easy... and yes, I realize how important volunteers are, and was grateful to be able to participate, and have a new found admiration for them BUT I still need to cross that finish line... it's become a part of how I grieve dad...
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Positivity is NOT about being soft.
It's about being SMART!
You suckkaaaaaaa! ;)