Hi, what about recording a short 2"30 video with your pitch. It would be an ideal exercise for brevity and also for crowdfunding. An associated brief Powerpoint presentation would be great too.
My advice would be
1. keep it simple and straightforward, no jargon
2. 1 idea per slide, talk in short "tweetable" sentences
3. Outline suggestion would be

a) describe in simple terms the business problem you solve for your potential customers "we found out that businesses had problems doing such and such"
b) how your solution (B2B SaaS portal) is proposing to solve this issue for businesses
c) what benefit for potential business clients
d) what benefit for your investors (if businesses buy into that and you fund my business, this is what you get in return)
e) how you propose (strategy) to reach that market by using assumptions (1 low assulmption, 1 medium, 1 optimistic) showing for all 3 that there is a benefit in terms of ROI for investors.
I suppose that if you wanted to go further, a short Clarity consulting call would be recommended. After all this is what it was made for.

HTH