For Point of entry, you should have a sediment filter and a carbon filter at a minimum, then a additional filtration for drinking water. Jumbo filters are better for flow and lifetime, but are bigger. So, from the spigot or pump that is pulling water out of the lake/river you would need
Essential System or Jumbo Essential System - This could either put water in the tank or pressurize your plumbing. Removes sediment, chemicals, taste/odor and giardia. You could also use the Virus Hero South of the border south of the border system, which adds a 0.2 micron filter to reduce/remove bacteria before it gets to your RV.
Drinking water system could be the Ultrapure Premium or the Custom RO. RO removes everything from the water, UP removes bacteria, lead, heavy metals, fluoride, chloramines, arsenic, but leaves in the dissolved minerals.
As far as the kit to remove water from lakes and streams, Remco makes one that we carry... It is self contained and includes the pump, hoses and filters you need to get the water out. If not this one, you will need a delivery pump that has coarse filters on the input, and enough power to push the water through the filters to the RV to fill the tank.
I also recommend Purogene as an additive to the tank to kill pathogens that might get through the POE filter system. This is great for purifying water that you put into a tank. Purogene has been used for decades by the airlines to purify and sanitize their water systems.
Here is a video of one guy's setup
12 Volt water pump, Shurflo pump and Water Filter for filling RV Caravan tanks, or camping shower