Adding the turbine and meter is extremely easy on the 7000, you can see it in my video link below. Am I reading correctly that you only get 50 gallons per day out of your well? A meter is not normal on a backwashing system, but it is not unheard of either. I prefer to backwash iron removal medias on a regular basis, rather than on a meter since the amount of sediment buildup can et excessive, and thus requires longer backwashes. You could try the meter and set it to 500 gallons, and watch the backwash to see how long it takes to run clear. Then do it again except put the meter to 1000 gallons and do the same test.
Estimating your average daily water use is normally ok for a filter since you are not using a consumable like salt.
Let us know how you are going to proceed.