Friendly but formal letter

Dear John,
I have one a question for you. (o, May I ask a favor.) Do you have any space in your house for two bikes and two exhausted guys?
I am going to travel by bike with a friend, from his town to yours, all across the country and with stops along the zig-zag route. We will start by the end of June, and I am not sure how long it will take. I will be telling you let you know upon my arrival.
Yours Sincerely,
Mike.

Friendly but formal letter

Dear John,
I have a question for you. (I have a favor to ask you.) Do you have any space in your house for two bikes and two exhausted guys?
I'm going to travel by bike with a friend, from his town to yours, all across the country and with stops along a zig-zag route, starting at the end of June. I'm not sure how long it will take, I will tell you upon my arrival (I will tell you when I know for sure. OR I will tell you when I have a better idea of my arrival date).
Yours Sincerely,
Mike