diff --git a/cmd/dartboard/subcommands/deploy.go b/cmd/dartboard/subcommands/deploy.go
index 95f669e..236b6c9 100644
--- a/cmd/dartboard/subcommands/deploy.go
+++ b/cmd/dartboard/subcommands/deploy.go
@@ -114,7 +114,7 @@ func Deploy(cli *cli.Context) error {
 	return GetAccess(cli)
 }
 
-func chartInstall(kubeConf string, chart chart, vals map[string]any) error {
+func chartInstall(kubeConf string, chart chart, vals map[string]any, extraArgs ...string) error {
 	var err error
 
 	name := chart.name
@@ -126,7 +126,7 @@ func chartInstall(kubeConf string, chart chart, vals map[string]any) error {
 
 	log.Printf("Installing chart %q (%s)\n", namespace+"/"+name, path)
 
-	if err = helm.Install(kubeConf, path, name, namespace, vals); err != nil {
+	if err = helm.Install(kubeConf, path, name, namespace, vals, extraArgs...); err != nil {
 		return fmt.Errorf("chart %s: %w", name, err)
 	}
 	return nil
@@ -190,7 +190,29 @@ func chartInstallRancher(r *dart.Dart, rancherImageTag string, cluster *tofu.Clu
 
 	chartVals := getRancherValsJSON(r.ChartVariables.RancherImageOverride, rancherImageTag, r.ChartVariables.AdminPassword, rancherClusterName, rancherClusterURL, r.ChartVariables.RancherReplicas)
 
-	return chartInstall(cluster.Kubeconfig, chartRancher, chartVals)
+	var extraArgs []string
+	if r.ChartVariables.RancherValues != "" {
+		p, err := writeValuesFile(r.ChartVariables.RancherValues)
+		if err != nil {
+			return fmt.Errorf("writing extra values file: %w", err)
+		}
+		defer os.Remove(p)
+
+		extraArgs = append(extraArgs, "-f", p)
+	}
+
+	return chartInstall(cluster.Kubeconfig, chartRancher, chartVals, extraArgs...)
+}
+
+func writeValuesFile(content string) (string, error) {
+	p, err := os.CreateTemp("", "values-*.yaml")
+	if err != nil {
+		return "", err
+	}
+	if _, err := io.WriteString(p, content); err != nil {
+		return "", err
+	}
+	return p.Name(), nil
 }
 
 func chartInstallRancherIngress(cluster *tofu.Cluster) error {
diff --git a/darts/aws.yaml b/darts/aws.yaml
index f8ae591..c151ca4 100644
--- a/darts/aws.yaml
+++ b/darts/aws.yaml
@@ -77,6 +77,10 @@ chart_variables:
 #  rancher_image_override: rancher/rancher
 #  rancher_image_tag_override: v2.8.6-debug-1
 
+# Set arbitrary helm values (in yaml format) for installing Rancher
+#  rancher_values: |
+#    features: "my-feature-flag=true"
+
 test_variables:
   test_config_maps: 2000
   test_secrets: 2000
diff --git a/darts/azure.yaml b/darts/azure.yaml
index 69a3d23..17a419a 100644
--- a/darts/azure.yaml
+++ b/darts/azure.yaml
@@ -103,6 +103,10 @@ chart_variables:
 #  rancher_image_override: rancher/rancher
 #  rancher_image_tag_override: v2.8.6-debug-1
 
+# Set arbitrary helm values (in yaml format) for installing Rancher
+#  rancher_values: |
+#    features: "my-feature-flag=true"
+
 test_variables:
   test_config_maps: 2000
   test_secrets: 2000
diff --git a/darts/k3d.yaml b/darts/k3d.yaml
index 451b63c..1819145 100644
--- a/darts/k3d.yaml
+++ b/darts/k3d.yaml
@@ -59,6 +59,11 @@ chart_variables:
 #  rancher_image_override: rancher/rancher
 #  rancher_image_tag_override: v2.8.6-debug-1
 
+# Set arbitrary helm values (in yaml format) for installing Rancher
+#  rancher_values: |
+#    features: "my-feature-flag=true"
+
+
 test_variables:
   test_config_maps: 2000
   test_secrets: 2000
diff --git a/internal/dart/recipe.go b/internal/dart/recipe.go
index aaa18f9..3471339 100644
--- a/internal/dart/recipe.go
+++ b/internal/dart/recipe.go
@@ -32,6 +32,7 @@ type ChartVariables struct {
 	RancherMonitoringVersion    string `yaml:"rancher_monitoring_version"`
 	CertManagerVersion          string `yaml:"cert_manager_version"`
 	TesterGrafanaVersion        string `yaml:"tester_grafana_version"`
+	RancherValues               string `yaml:"rancher_values"`
 }
 
 type TestVariables struct {
diff --git a/internal/helm/helm.go b/internal/helm/helm.go
index 0553798..e79f2f9 100644
--- a/internal/helm/helm.go
+++ b/internal/helm/helm.go
@@ -25,7 +25,7 @@ import (
 	"github.com/rancher/dartboard/internal/vendored"
 )
 
-func Install(kubecfg, chartLocation, releaseName, namespace string, vals map[string]any) error {
+func Install(kubecfg, chartLocation, releaseName, namespace string, vals map[string]any, extraArgs ...string) error {
 	args := []string{
 		"--kubeconfig=" + kubecfg,
 		"upgrade",
@@ -46,6 +46,7 @@ func Install(kubecfg, chartLocation, releaseName, namespace string, vals map[str
 		}
 		args = append(args, "--set-json="+valueString)
 	}
+	args = append(args, extraArgs...)
 
 	cmd := vendored.Command("helm", args...)
 	var errStream strings.Builder