On a 2006 S Class 320CDI with 20" AMG (5 spoke) wheels with tirfit system and AMG body kit I would like to know if it is possible to retro fit some sort of spare wheel (either to match or space saver type) ition ncluding the boot section so that all would appear as original equipment. If it is possible I would like an idea of which parts to get. I frequently travel long Spanish and French motorways and would feel more comfortable with a wheel. Thank you