I made a lot of progress with my steel full suspension frame lately:
As previously mentioned, this is not going to be used for high speeds or jumps. I "designed" it specifically for very difficult alpine trails. Hence the flat headset angle and the short wheel distance.
I just need to add some brake sockets, order some parts do some welding. After some time, I will shorten the seat tube, and remove the top tube and place it much lower. This enables me to lean back as much as possible during steep trail segments.