OK as long as you’re preventing overlap thats fine.
You need to be more specific when talking about the container’s IPs here.
“But using 10.30.10.1 for the lxd container and 10.30.10.0/24 for the docker0 net should be no problem” - this doesn’t really make sense I’m afraid 
Your container will need to have 2 IPs, one IP on its eth0 interface in the subnet 10.30.0.0/16 (but not in the subnet 10.30.10.0/24). In your original image here Hide container network interfaces from host - #3 by DreamTexX it had the IP 10.30.163.116. This is the IP you’ll use in the static route’s via section.
The container will then have another IP, 10.30.10.1/24 on its docker0 interface.
Your container cannot use the IP 10.30.0.1 on its eth0 interface as that is being used by the internal bridge interface on the LXD host.
The static route will then say “reach 10.30.10.0/24 via the container’s IP on the internal bridge (10.30.163.116)”.