Forced Tunneling, Vnet to Vnet (Resource Manager)

I have two Vnets in Azure that both have been configured with Virtual Gateways for Vnet-to-Vnet connectivity. Each Vnet has two subnets: 'Front', where a single VM is located, and 'GatewaySubnet', where the Gateway is located.

As a proof of concept, I want to:

1. Configure forced tunneling so that all traffic originating from the VM in Vnet 1 is forced to Vnet 2.
2. Configure IP forwarding on the VM in Vnet 2 so that all traffic to and from VM 1 is forwarded correctly.

I am using Azure Resource Manager, and I'm following these instructions to configure my User Defined Routes:

https://azure.microsoft.com/en-us/documentation/articles/virtual-network-create-udr-arm-ps/

Question 1

I understand I need to configure a route for the Front subnet in Vnet 1 such that:

$route = New-AzureRouteConfig -Name vnet1vpngateway -AddressPrefix 0.0.0.0/0 -NextHopType VirtualNetworkGateway

And I also understand I need to configure IP forwarding on VM 2 (located in Vnet 2), such that:

$nicvm2 = Get-AzureNetworkInterface -ResourceGroupName networkingRG -Name NICVM2

$nicvm2.EnableIPForwarding = 1

Set-AzureNetworkInterface -NetworkInterface $nicvm2

As far as routing goes, what else do I need to do?Do I need to add UDR to the Gateway Subnets on Vnet 1 and Vnet 2?

Question 2

When trying to run the following commands in PowerShell to add a routing table to the Front subnet in Vnet 1:

Set-AzureVirtualNetworkSubnetConfig -VirtualNetwork $vnet -name 'Front' -AddressPrefix 0.0.0.0/0 -RouteTable $table

Set-AzureVirtualNetwork -VirtualNetwork $vnet

...I get the following error:

I do indeed have a subnet called 'Front' in my testVnet1:

Any idea of what is going on?