I had the slide-out rear bumper on my 2013 Heartland Trail Runner, which is basically the same rear rack.
I found it such a PITA to strap the bikes up each time that we went out with it that the bikes hardly ever left the rack because i didn't want to deal with strapping them back on again.
Skinned knuckles...dropped lots of quarters in the swear jar...
Had that trailer for two years and almost every single photo (and I take lots of photos) that I took of that Trail Runner, the bike are almost always still on the rack.
Finally just relented to not taking the bikes anymore.
And when I traded it in for my 5'ver, they had two of the same model side by side...the only difference between the two was that one had the flip-down rear bumper rack.
I bought the one without the rack and never regretted it.