If I were you, I'd do the following:
1) Temporarily get rid of the ads. I can't imagine you are making that much off of them right now and your short term focus should be on increasing user growth to ensure the long term viability of the site. At the very least, tone them down a little.
2) Do a few other things to give the site a clean/modern look. Can you find a full width panorama image?
3) Fix the annoyances (wiki issues, photo upload, etc.)
4) Give a little love to a few of the other pages. E.g. the home page is silly. https://www.clubtread.com/
The copyright at the bottom is 2001-2008 and it's still in the name of TallTech Systems Inc. It hasn't been updated in years. Anyone from the internet who lands at ClubTread and a few of the other alternatives may assume that this site is on the way out (based on the visual appearance,) and go elsewhere.
If you want users to invest in putting their trip reports here, you need to also invest some time.
5) Do a bit of promotion. Look at trip reports that are getting a lot of views and see if the author wants to turn it into a highlighted trip report which might be posted on the homepage in a better format and potentially co-posted on a blog like the Daily Hive. I could also imagine someone on this forum writing a monthly post (based on all of the observations in the trip reports) to give a bit of a summary on trail conditions (e.g. the snowline in June is around XX) and I could see that getting shared more broadly.
6) Improve the SEO
. One simple thing that could be done is to go through the trail wiki and provide links to one or more trip reports for the popular trails.
Something we can all do is comment more on eachother's posts. Let's be honest - if you put in the time to write a trip report and it only get 1 or 2 responses, you may question the value in what you are doing. I think that if it weren't for KARVITK, a lot of users might have left a long time ago. That guy is amazing. His trip reports have been valuable but he has also made sure that no TR ever goes with zero responses.