The "Work in Progress" subforum is, as the name suggests, for content that is actively being worked on. Ideas and suggestions unfortunately do not fall into that category.
I'd also suggest that the most effective way to get content that you want in Omsi is to make it yourself. Those who have the experience and knowledge to make something have gained that experience because they wanted something in Omsi and so are involved in their own projects, very unlikely to take on additional projects that other people want. Good luck and have fun mapping for Omsi.