Home glass shop is the best way but they will most likely want you to remove the entire window frame from the trailer.
They will be able to check and match the color of the glass cut new glass to size and install it into the moveable part of the frame.
I will however suggest that it would be a wise move to have them TEMPER the replacement glass. From the looks of the large sharp shards the manufacture did not temper the glass and that is a very dangerous thing..
Tempering the glass is a chemical and heat treatment which will strengthen the glass AND at the same time will make it much safer if the glass gets broken in the future. Tempering puts a specific amount of surface tension on the glass which when broke will make the glass shatter into millions of less sharp and harmful pieces.
Tempering must be done after the glass has been cut and fit.
Most home glass shops will have to send this out to have done for a small additional fee but it is well worth it since the glass will be stronger and resist breakage better.
Don't bother with auto glass shops unless they do custom glass for chopped hot rods..