The next step are to consult with the client, showing the trade studies. Do they still want those requirements?
In any case it is important to try getting a better component weight estimation to be able to find out where the CG of the aircraft is placed, so wings, tails and landing gear can be placed at the correct position on the next sketch. After that performance should be recalculated in a more correct manner.
There is also a need to shorten the landing distance by 60m using some tecnical solution (unless the customer builds longer runways).
On the next sketch there should also be structural load carriers, so we can do some optimization concerning the part of the production that is constrained by the conceptual design. The landing gear position in retracted position also needs some more considering.