I found Firefish which is a better alternative to the standard Mastodon application. It’s compatible with Mastodon and has better features. It allows users to create web pages and the character limit is 3,000 instead of the 500 on Mastodon. It feels like a good limit for the type of site that it is. Plus this means that it can handle long posts from users on customized Mastodon instances.
Unless they recently changed things, the creator said specifically that he isn’t going to add the character limit as an option. I can understand that since sometimes you need to restrict certain features based on the goal of the project. I think it would be fine because I don’t think it will turn into Medium since the interface isn’t really set up for that.