I used two whole house filters connected together with a brass nipple and 3/4" pipe to hose fittings brass adapters at each end.
The first was a sediment filter, and the second a charcoal filter. They did not really slow down the flow until they actually needed to be replaced.
In fact we used a pressure regulator most of the time because the pressure was too high in many city water supplies for the RV plumbing.
However, there is something to be said for your way. You see the charcoal filter adsorbs the chlorine, if any, in most city water supplies.
Letting that small amount of chlorine through your plumbing and water heater cuts down on the frequency of sanitizing them as it cuts down on the algae and bacterial blooms, however harmless they may be.
So there is something to be said for putting the charcoal filter only on the drinking water tap. If you want to increase the flow there you can just put a whole house filter housing and charcoal filter under the sink, instead of using the spigot type of filter.