This is one of the most popular mods in the Casita community. It adds a storage tray over your propane tanks on the tongue of the trailer. It's a perfect place to put a generator, though people also use it for other purposes.
The tray we used (and that everyone recommends) is the Stromberg Carlson CC-255 Trailer Tray.
It's rated to hold 300lbs, which is a lot. For reference, our new generator (a Westinghouse WGen3600DF with 4650 peak watts, 3600 running watts) weighs 109lbs.
Potential problems
But keep in mind that this will add to your tongue weight. If you're already near the max tongue weigh for your tow vehicle, you may need to add a weight-distribution hitch. Andersen No-Sway Weight Distribution Hitches are what Casita sells and what most owners recommend.
This tray will also make it harder to access your propane tanks, especially if you have the standard hard cover. There are solutions to this problem, which I think we'll cover in a future post. But the simplest solution is to get a soft cover like this one. That's what we did, but I can't recommend it. Those soft covers are very flimsy and ours started tearing after a day or two on the road. Maybe a more durable soft cover would work better, but we've only tested the one.
The only other downside to adding this trailer tray is that it partially blocks the tongue jack cranking arm. If you have an electric tongue jack, you don't have to worry about this. But if you have a manual tongue jack, you'll need to be careful to avoid busting your knuckles.