Hard to set the figwheel configurations

Currently, the the figwheel configuration will be generated by figwheel-config

(defn- figwheel-config [path main]
  {:duct.server/figwheel
   {:css-dirs ^:displace ["resources" "dev/resources"]
    :builds   ^:displace
    [{:id           "dev"
      :figwheel     true
      :source-paths ["dev/src" "src" ]
      :build-options
      {:main       main
       :output-to  (str path "/js/main.js")
       :output-dir (str path "/js")
       :asset-path "/js"
       :closure-defines {'goog.DEBUG true}
       :verbose    false
       :preloads   '[devtools.preload]
       :optimizations :none}}]}})  

which is hard to change like ':figwheel {:on-jsload "..."}', the only option is to override all the figwheel config.
when people needs multi builds (e.g. js per page, serverside rendering specific js) for development would be really hard to change the config.

Currently, I could only hard code all the configs under :duct.server/figwheel and :duct.compiler/cljs. It is not ideal, since the path and main would be hard-coded.

Would it be any better way to do it? like the boot-reload, .cljs.edn?

Start at the figwheel-config function and inspect how :duct.server/figwheel and :duct.compiler/cljs are currently supplied. Compare the requested flexibility with the mentioned boot-reload and .cljs.edn approaches; the work is complete only when a concrete configurable approach supports changes such as :on-jsload and multiple development builds.