diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index da138d53d..412a6e748 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -1027,9 +1027,10 @@ public:
         if (typeinfo->default_holder) {
             sh_load_helper.loaded_v_h = v_h;
             sh_load_helper.loaded_v_h.type = get_type_info(typeid(type));
+            type_caster_generic::load_value(std::move(v_h));
             return;
         }
-        throw std::runtime_error("BAKEIN_WIP: What is the best behavior here?");
+        throw std::runtime_error("BAKEIN_WIP: What is the best behavior here (load_value)?");
     }
 
     template <typename>
@@ -1037,11 +1038,29 @@ public:
 
     explicit operator std::unique_ptr<type, deleter>() {
         if (typeinfo->default_holder) {
-            return sh_load_helper.template loaded_as_unique_ptr<deleter>();
+            return sh_load_helper.template loaded_as_unique_ptr<deleter>(value);
         }
         pybind11_fail("Passing std::unique_ptr from Python to C++ requires smart_holder.");
     }
 
+    bool try_implicit_casts(handle src, bool convert) {
+        for (auto &cast : typeinfo->implicit_casts) {
+            move_only_holder_caster sub_caster(*cast.first);
+            if (sub_caster.load(src, convert)) {
+                value = cast.second(sub_caster.value);
+                if (typeinfo->default_holder) {
+                    // BAKEIN_WIP: Copy pointer only?
+                    sh_load_helper.loaded_v_h = sub_caster.sh_load_helper.loaded_v_h;
+                } else {
+                    throw std::runtime_error(
+                        "BAKEIN_WIP: What is the best behavior here (try_implicit_casts)?");
+                }
+                return true;
+            }
+        }
+        return false;
+    }
+
     static bool try_direct_conversions(handle) { return false; }
 
     smart_holder_type_caster_support::load_helper<remove_cv_t<type>> sh_load_helper; // Const2Mutbl
diff --git a/include/pybind11/detail/type_caster_base.h b/include/pybind11/detail/type_caster_base.h
index 779bb15a4..5efdf308b 100644
--- a/include/pybind11/detail/type_caster_base.h
+++ b/include/pybind11/detail/type_caster_base.h
@@ -887,7 +887,8 @@ struct load_helper : value_and_holder_helper {
     }
 
     template <typename D>
-    std::unique_ptr<T, D> loaded_as_unique_ptr(const char *context = "loaded_as_unique_ptr") {
+    std::unique_ptr<T, D> loaded_as_unique_ptr(void *raw_void_ptr,
+                                               const char *context = "loaded_as_unique_ptr") {
         if (!have_holder()) {
             return unique_with_deleter<T, D>(nullptr, std::unique_ptr<D>());
         }
@@ -896,17 +897,8 @@ struct load_helper : value_and_holder_helper {
         holder().ensure_is_not_disowned(context);
         holder().template ensure_compatible_rtti_uqp_del<T, D>(context);
         holder().ensure_use_count_1(context);
-        auto raw_void_ptr = holder().template as_raw_ptr_unowned<void>();
 
-        void *value_void_ptr = loaded_v_h.value_ptr();
-        if (value_void_ptr != raw_void_ptr) {
-            pybind11_fail("smart_holder_type_casters: loaded_as_unique_ptr failure:"
-                          " value_void_ptr != raw_void_ptr");
-        }
-
-        // SMART_HOLDER_WIP: MISSING: Safety checks for type conversions
-        // (T must be polymorphic or meet certain other conditions).
-        T *raw_type_ptr = convert_type(raw_void_ptr);
+        T *raw_type_ptr = static_cast<T *>(raw_void_ptr);
 
         auto *self_life_support
             = dynamic_raw_ptr_cast_if_possible<trampoline_self_life_support>(raw_type_ptr);
@@ -943,6 +935,7 @@ struct load_helper : value_and_holder_helper {
         if (self_life_support != nullptr) {
             self_life_support->activate_life_support(loaded_v_h);
         } else {
+            void *value_void_ptr = loaded_v_h.value_ptr();
             loaded_v_h.value_ptr() = nullptr;
             deregister_instance(loaded_v_h.inst, value_void_ptr, loaded_v_h.type);
         }