I made a good Loonie sized ding in my trailer which was pretty much limited to the gelcoat. I did as John suggested and got some from Escape
, which they provided for free. It was a 500ml pop bottle full, which was WAY more than I needed, but I just added a wee bit of hardener to a couple tablespoons, and fixed things up nicely.
You can easily pick up a gelcoat repair kit in many locations and mix up your own with a colour to match close enough. They are not pricey and do the job well.
Lots of videos out there to show how to do the fix.