I PM'd you - not realizing you started a new thread. If you get Corsa C or Tigra, you can do as I did (I have a LHD Opel Combo Tour) and do away with the front risers (they're separate to the runners) and the C/Tigra will go straight in, but you sit some 25mm/1" lower. Or, you can make something, or get a tall nut with a big enough hole for the Torx bolt to pass through, weld it onto the rear and maintain the previous height.
If you like the Combo C passenger seat that folds fully forward for long loads, that's a Combo C only feature, but 3dr and Tigra seats will allow them to flick forward enough for pipes and poles - just not long boxes. Let me know if you are in Spain and have LHD.