Hi
@Laura K and welcome to the site.
You will have to post a few close up pictures before we can offer any help in repairing your leak.
In addition, you can locate the leak by making up a mixture of a cup of water and a half teaspoon of liquid dishwashing detergent. Pour the mix into a spray bottle and spray the fittings and hoses around the suspected leak (or apply with a paint brush). Try not to soak the regulator or solenoid valve to avoid corrosion. The leak will show as bubbles and you can go from there.
I do not know what your experience in dealing with propane is, but please be aware that making a mistake with propane on a boat is the most dangerous mistake you can possibly make.
The hose fittings are non-standard, so I cannot just replace the hose
The statement "non standard" is definitely cause for concern here. That's why a few photos are required.