Various EP trip reports can be found at this website by Ingrid Schmidt.
Yearly EP's have been taking place since 1996:

EP1 took place in Antwerp, Belgium, on june 14th - 16th 1996. There is a web album by Ton van Bart.

EP2 took place in Neuenbürg, Germany, on june 6th - 8th 1997. See the web album by Ton van Bart.

EP3 took place in Moena, Italy, on june 11th - 13th 1998. Ton has yet another web album for this one.

EP4 took place in Hindas, Sweden, on august 11th - 14th 1999.

EP5 took place in Lynmouth, England, on june 7th - 11th 2000.

EP6 took place in Lisbon, Portugal, on july 9th - 13th 2001.

EP7 took place in Törwang, Bavaria, Germany, on july 4th - 7th 2002.

EP8 took place in Rouge Gazon, France, on july 3th - 7th 2003. There is a trip report online, written by Stelios Hatzopoulos. Lots of pictures!

EP9 took place in Zwartsluis, the Netherlands, on july 1th - 4th 2004. Read the trip report by Stelios and see a web album by Paul Hounslow.

EP10 took place in the Ardennes, Belgium, on june 30th - July 3th 2005.

Hotel Pax Montana EP11 took place in Flüeli Ranft, Switzerland, on july 6th - 9th 2006. There is a trip report by Stelios, a web album by Ton van Bart and another web album by Sven-Erik Tiberg.

EP12 took place in the Dolomites, Italy, near the EP3 area. There are several web albums, for instance made by Thomas Winterfeld and by Mo Maassen.

EP13 took place in the Harz, Germany, on june 26th to 29th, 2008.

EP14 took place in the Jura, France, june 25th to 28th, 2009.

EP15 was held in Denetice, Czech Republic, july 1 to 4, 2010.

EP16 took place in Hindas, Sweden, july 21th to 24th, 2011.

EP17 was held in Wittlich, Germany, from june 28th to july 1st, 2012.
There is already one flickr album by Armand (opens in a new window).

EP18 was held in Friuly, Italy, from july 4-7th, 2013.

EP19 took place in Ryn, Poland, from 3 to 6 july 2014.

For EP20 the Europrez circus returned to the EP10 site in Buellingen, Ardennes, from 25 to 28 jun 2015.