Even most RV systems use directional antennas simply because they perform better [once aligned], but there are omni models like the one Dutch mentioned. It sounds as though you need the antenna moreso than the booster amp, just to get around the trees.
Whether omni or directional, you still have to get the antenna up where the signal is. In your case, that may mean high enough to get away from the tree shadow.
A directional antenna isn't a big deal to set up in most cases. Basically trail & error works as long as you can climb up & down OK or have a pal to check the signal reading as you turn the antenna. A smart phone app that shows signal strength in real time is easier to use than just the typical bars on the phone screen. The bars don't respond quickly are very accurately either. There are also cell locator apps that identify which direction the cell tower is from where you are, so you know basically where to aim the antenna.
The other problem with booster is the typically limited re-broadcast inside the building. Most "home" systems have very limited range inside, so you need one of the larger commercial/office systems to get usable coverage inside. Those claims of 5000 sq ft must be in some big open barn with reflective interior walls, cause few systems cover even a 1000 sq ft house very well. I had a so-called 1000 sq ft system in my 375 sq ft motorhome and I still had to stay within about 5 ft of the inside antenna. The effective range was more like 50 sq ft. and did not penetrate walls at all. Buy the maximum inside coverage range you can afford!
