How long should a appeals letter be for the board of reviews? Will it be accepted if dated on the 2oth day?

I have been trying to find help with my case ust to be told they do not handle unemployment cases, I finally got a letter together because I just did not know what to do or write, to the board of reviews, I had 20 days but I had to get doctor records which took some time, will I be able to appeal my case still if it is sent out on the 20th day? I was unfortunately calculating the day when I received the denial letter and not the day the letter was dated for I misunderstood the 20th day rule, I have a 4 page letter though is that too long for the board of reviews, and I have 10 copies of proof no other interviewer has taken in proving I did not quit my job but was fired do to my health. I just need to know will they accept my appeal letter , the denial letter was dated October 17th, 2014 and today is the 20th day I was sending it out today because I also do not have the funds to pay for it and was waiting for my son to get paid today. Also how much is too much information in writing it