This is not possible with the built in "virtual controller assigned" DHCP method. There may be a workaround where you can create a VLAN with a local DHCP scope and then src nat all the traffic out of the VC. However, you would then be responsible for trunking the created VLAN ID on the LAN.
You're easier option is to use a VLAN on the LAN and a DHCP in the LAN as well to assign the option value...