My reply addresses what you said specifically.. a small cargo carrier with a bike rack attached. I have a 17 ft Casita
that I used a cargo carrier on for a year with NO problems. My tongue weight and back-end weight were balanced correctly and I never had any difficulties until I changed to a cargo carrier made to attach a bike rack that came with it. Despite my best efforts, the combination just put too much weight too far out behind my little trailer. I experienced that out-of-control pendulum action 3 times in 160 miles and acquired a head full of new gray hair.
Upon arrival at my destination, I also found that a steel pin which fit up into the post of the bike rack had sheered off in the first 28 miles of the trip, allowing the bike rack to pivot left to right on the securing bolt, causing the trailer to pendulum. I tried speaking to the distributor whose name is on the item, but they would not hear anything about the safety defect in their product. Would not even discuss it. However, the company I purchased it from will no longer sell it. It shows it as no longer carried.
Here is the name of the combo I would highly recommend you do not buy:
3-Bicycle 60" Folding Cargo Carrier Basket Rack Combo for 2" Hitches
sold by Rage Power Sports on Amazon.com.
RPS refuses to take responsibility for their product or any damages caused saying they do not manufacture them, only distribute them with their name on it. I have also found the same item sold under the name Blue Ox. Buyer beware!
I have seen another type cargo/bike carrier setup that places the bike rack between the hitch and the cargo carrier, but due to the spare tire placement on the Casita
, that one would not work for me.
My O-p-i-n-i-o-n and experience is that the combination of the two racks behind a small trailer just extends the weight too far out behind the trailer and affects the overall balance and stability. I won't do it again.
Just my 2 cents.