Sorry for the long delay in replying. Been away from the forum. My extension works well for me. With out a counter weight
on the back end it will be very tongue heavy. In excess of 500 pounds if they build it with substancial materials. I have about 300 pounds on the rear with the cargo box and the rack that supports it. That gives me between 250 and 350 pounds tongue weight
. When I am going any distance I have a 3/4 ton pickup with a Equalizer brand hitch. Rides beautifully with that configuration. When I have gone on trips of less than 50 miles I have towed slowly with my PT Cruiser. I do not advise anyone to do that. I consider myself a skilled driver and am familiar with the local roads.
I like the 30" by 60" platform in front. It carries my 4 wheel handicapped scooter just fine. I should have made it 32" but it works as is.
Even with the equalizer hitch there can be some up and down movement of the tongue on rough roads. With the PT on local roads, I have to be very aware of any conditions that would cause the tongue to oscilate up and down. there is a lot of weight
far away from the wheels, so any up or down motion has a lot of mass in motion.
The Outback is very finely balanced on the wheels and care must be taken when adding weight front or rear. Add more than a couple hundres pounds (100 Kilo) to rear only and there won't be enough tongue weight. Add more than a couple hundred pounds to front only and there will be too much tongue weight.
My biggest regret is not getting an air conditioner. Second biggest regret is now shower.
I also raised my trailer 3" and changed the axel to 3,500 pound capacity. I also upgraded my tires
to load range D. With the additions front and rear, I was right at the limits for tires
and axel. Reason for the 3 inch raise was for ground clearance front and rear because with the extended length, the trailer would scrape the rear or drag the tongue on some drive entrances.
I didn't know all of that when I started the process. I now have a 21 foot trailer with a 10 foot living area, registered as a 13 foot trailer.