I have used all 3 types (trailer tongue mounted, front hitch and roof top) of bike racks and they all work well. You need to decide where you want the extra weight to be distributed.
Can you afford the extra weight (###) of the 5 bikes plus the frame mount as well as the bike rack weight on the tongue ? Will your WD bars support it without the expense of installing heavier bars. I would get a real tongue weight prior to buying the tongue rack system.
The YAK system would allow the extra weight to be spread out on the TV axles and might be worth the cost.
Front hitch carriers keeps it on the front axle but it adds a lot of frontal area carrying all 5 up front. You might have a small issue to be able to swing between trees if you maneuver into a tight campsite.
Give some thought to splitting the load between a front hitch rack and a trailer tongue rack.
That would help distribute the load but the expense will be pushing the YAK price which might end up being the easiest way to transport for you .