Glad you like Juno so far.
I think you've got roughly the right idea in terms of hacking on Juno, but I'll elaborate a bit on my workflow.
You can do almost all development from within Juno itself, i.e. you don't need an LT clone. You can of course edit and eval into Jewel.jl while Julia is running. If you open up one of the plugin
.cljs files in Juno and save, you should see that it builds the plugin, and you can also eval to change things at runtime. It is a bit spread out, unfortunately, but the various plugins are listed here.
Once you get used to the workflow it's pretty nice – you should very rarely have to restart Julia to see changes, and almost never restart LT itself.