How do I get a Schengen Visa for walking the Camino de Santiago?

The question was: The Spain Consulate in Mumbai, India, requires an ‘invitation letter’ sent by some firm/company/tourist organisation, etc. to the traveller in order to obtain a visa! How can I make this work I dont know! So anyone who is not a EU citizen and has walked the Camino, with no official ‘invitation letter’ or a…