I guess the best you can do is read the first three pages (in the nomination post) and ask yourself if you are prepared to do 15 pages per week.
Of course the first few pages are always harder, since you get used to the author’s writing as you read, and certain terms are often repeated that you had to look up before.
It is totally up to you, of course. If you feel like reading it, go for it! Wild abandon and whatnot.
I do remember thinking that maybe I would’ve enjoyed the reading a bit more if I didn’t start off trying to read as difficult books as I did, though. Reading (much) above your level makes it harder to enjoy the writing and I ended up getting bored with the chore of slugging through word by word. Whether this would be the case for you and キノの旅, you will have to judge for yourself.