No , I dont know this company .
My advice : for one night at Gavdos beaches you dont need tent and a sleeping bag . First of all , in August its very warm in the night time . Most of the people who sleep at the beach they only have a thin mattress and a scarf, using trees or bushes with their shadow under the sky. At the sandy Sarakiniko Beach and Ag. Ioannis Beach you can find a sleeping place, also in Lavrakas or Korfos .