The problem is everybody could say this. You cant ask for a investment without any showing or proofing material. This is not cause everybody think you a scammer - this is because everybody want to see that's real.
So show what you got so far.
As I said above, I'd be happy to show both the GDD, and the Monetization Documents to anyone who was interested. I can send them to you if you'd like.
Such documents dont help those who lend you money get it back. I think your best bet would be to launch a kickstarter or a indiegogo campaign.
This isn't really a loan. It's an investment and it could go either way to be honest. If the game sells then we should all make money, if it doesn't sell then we're all losing money. We've considered going to kickstarter but we really don't like the idea of setting an "investment goal" that, if not reached results in losing what funds people have offered us.
What I can promise is that we're busting our asses working on this game, we've got a lot invested in this project both monetarily and emotionally.