To help us recommend the suitable solution, could you please tell us a little more about how you would like to use it?
For example, is your main goal to provide Internet access inside the mobile home for phones, laptops, or other devices?
What is most important to you: longer Wi‑Fi range, a more stable connection, higher speed, connecting several devices, or a simple portable setup?
When I was staying at a place without WIFI, but had a large deck where I could reach the local coffee shop’s WIFI from one corner, I put my tiny USB150 router on that corner running off a battery, inside a zip‑lock bag to protect it from the rain. Then I used my travel router inside so all my devices could get online through VPN. I visited the coffee shop regularly, so I did not feel bad using their WIFI.
You might be able to put a small router between your mobile home and the campsite’s router. Although the USB150 is no longer available, GL iNet still makes several small routers, like the AR300M16‑ext, that can run for an extended period off a battery. Stay away from their bigger routers, as they drain batteries quickly.
eric's suggestion above is a practical option for this type of setup.
One thing to keep in mind is that a repeater cannot significantly improve an already very weak Wi-Fi connection. The key is to place the router where the campsite Wi-Fi signal can still be received reasonably well, for example near a window or another location with less obstruction, and then use the router to provide Wi-Fi inside the mobile home.
What is difficult for me is, if you maintain the camp network and are permissionable I could easily say you could extend routers around the place via extension mode and if the software allows it (most vendor sdks don't do this), is allow fast roaming.
You could maybe also use astrowarp, as mesh is also designed to measure the best AP which fast roaming alone doesn't.
But if you don't have these permissions, one thing I can think of is trying to look for a router with high gain antenna I believe they also call it wifi HaLow.
But because it listens to the 802.11ah spec, I do not know if the camp side also must talk with this spec.... but I do know this type of connection works similar like a satellite dish and you need to target it more precisely.
^ from my short coming research both ends are required to speak this protocol, i also learned there are also halow usb dongles which can reach to 1km distance.