Keep in mind that boosting a WiFi signal has nothing at all to do with improving performance. If the park internet service "stinks" a booster will not help that at all. However, if you can take your computer to the office, close to the router and get good performance but you don't get good performance at your site then a booster "might" help. Each additional link in the network slows your speeds so any improvement will not be linear.
For a really good, inexpensive WiFi booster go to David Bott's website. He walks you through the setup and for about $100 you will have as good a setup as possible without a lot of effort.
https://outsideourbubble.com/secure-private-rv-wi-fi-and-making-a-better-park-connection-for-under-100/