Thank you very much for still not having given up on this!
Please regard this:
Kicksecure Forums Usage Instructions, Best Practices and FAQ
R3.2 has additional complications. ( sys-firewall [sometimes] broken, does not function as ProxyVM in Qubes R3.2 RC1 )
Try connecting sys-whonix to sys-net rather than sys-firewall to exclude another possible source of issues.
Unrelated. Documented here:
Control and Monitor Tor
Compare with a Debian based ProxyVM running Tor.
Not easy. “UnWhonix”, i.e. make Whonix-Gateway more similar to a Debian VM running Tor.
How-to: "UnWhonix" - enable clearnet networking
Then Tor should bootstrap as quickly as in non-Whonix VMs. Then re-add what Whonix does.