With limited access neither stile PEX clamps will be easy to use. The ring stile requires either a large tool with 18" arms, or the smallest tool is about 6" long but requires vice grips to squeeze it, making it longer, but maybe offset. The clamp stile ring works well, I am told, but still needs a tool to work it, and in close quarters may not work.
The sharkbite fittings are great, but often bulky and may not fit in your space.
There is a plastic RV type fitting which works on PEX too, I forget the name now, but it can be tightened with a set of pliers. Probably the smallest fitting and fairly easy to work with. Your RV dealer will have them, and some hardware stores.