If you are worried about ethical or legal concerns in running a presale in your current situation, just be very upfront with people the same way you are with us. Price yourself at a point where the people who take early risks can see 100x (or higher) returns "easily" given your understanding of the market and your business. People are willing to put money into a 2 man team with a dream, but you might have to lower your expectations of how much they are willing to put in.
What op need at this ground and time is advice and encouragement to exercise patience to work because thinking that immediately the work of yours is carried out and expose to the nation it will be easy to adopt, i think is wrong ideals, as you said here your expectations don't have to come too fast and desperate because is a newly developed project