I realize I can't "no bump" this and it's an old suggestion...
but blogs are lightly trafficked and seem to suit your purpose.
In order to make it suit that purpose though I would suggest you think hard about you are going to organize your journal prior to starting it since you can't edit a post past 5 minutes.
If you could you might do something like "entry 53: my day in Rome" or "I decided to change the format starting with post 68" etc.
So since you can't do that, think of a way around the edit and type the journal with the limitations in mind. Like how you are going to respond to people posting and how to do that. The information on how to link a particular post (with the number as a hyperlink) would be helpful.
Or each post having a subject matter within the beginning of the post?
Perhaps guidelines on how discussion would go within the journal since it seems like getting a journal clogged with a conversation might not be ideal for others browsing. Or perhaps a secondary thread for responses to said journal so that readers don't have to sift past that if they are just looking for entries.
Maybe the format for outside links and how to search for them on a search engine if people are leery about links or when posting pics make sure they are formatted correctly to be visible if they have text since guests can't see them when they click on them.
Also maybe that it might be an intermittent work over many years with long gaps or each day with an explanatory post if you'll be away. People do like to follow blogs but if they think it's a "dead blog" they may have less interest. I don't like to cater "too" much to other people with formatting but it is useful if you want to share to have it in a well laid out format.
As opposed to text walls or posts that are almost TL;DR (like this one maybe
)
Stuff like that.
I've been wanting to start a journal/blog for quite a long time despite the super light traffic to compliment other things I do on the net but I'll confess that the limitations have stopped me for a while. Thanks for the suggestion because it's expanded my horizons on that front