My brother and I installed the EcoHitch on their 2017 Bolt EV:
It took us about 2 hours. The hardest part was unclipping the two rear wheel arch trim - and one of the two plastic clips on the lower edge of the bumper cover broke, and I had to repair it with some electrical tape.
We varied from the instructions in one important way - shown in the lat 2 pictures. We left a 1.5" connecting strip to strengthen the bumper cover; making a hole, rather than cutting out the whole slot. This is now the third hitch my brother has installed - first on an i MiEV, and the second on his i3 REx. The i3 was MUCH more difficult.
We have over 20,000 miles on our Bolt, now. It is great not having to stay under the lease mileage budget!