How do i make this a permanent hook up?

You CAN'T legally make it permanent....Show more

I would NOT do that.  doing it then requires that the RV return to the exact spot -- within 1/4 to 1/8th inch in all directions.  You can shorten the flex and I recommend leaving a few inches excess to allow for the RV being returned or settling.  Note that if there is ANY danger of freezing, you need to consider that [no exposed trap] in your connection.  BTW, many jurisdictions require a building permit and land use permit if you make a 'permanent' connection or if someone regularly lives in the RV.  Fine for violation begins at several hundred dollars per day....Show more