The dynamic stealth mod changes mob AI so that they are less likely to see the player when sneaking. I use aqua acrobatics with toggle crawl, and I think it'd be a nice feature to have crawling affect the player's stealth level in the same way.

(If it would be too hard to include, another fix would be to make it so that the player is always "sneaking" when in the crawl state if a certain setting is enabled.)