That is incredibly awesome! Best of luck. I am very jealous as it sounds like a great adventure.
22 kms a day sounds manageable. But doing that for 90 days straight, you know you will have days, or for me it would be mornings, where you just have to power through.
Have you been in contact with the people at Guinness? Have they approved the attempt and the record keeping requirements? In my experience it is arduous to get them to officially recognize a record (unless you pay them to have a representative witness it) and they have to pre-approve everything. It took me about 18 months or something and lots of negotiation to get recognition for an act that was clearly a record. I would hate to see you not be recognized over some paper work problem or miscommunication.
But regardless, even if you do not get a record, raising awareness and money for a worthy cause is a great thing to do.