Complex sentence: Working with a borrowed tent, Laliberté then had to contend with difficulties with the European performers who were so unhappy with the Quebec circus's inexperience, that they had at one point sent a letter to the media complaining about how they were being treated.
Split into simpler sentences: Working with a borrowed tent, Laliberté then had to contend with difficulties with the European performers. They were so unhappy with the Quebec circus's inexperience that they had, at one point, sent a letter to the media complaining about how they were being treated.