Congrats on your new Pinnacle.
No you don't have to use a slider, but you should. I prefer the automatic sliders because it only takes once to forget and you have a problem. I have a Pullrite auto slider and it's great. The auto sliders are not cheap but neither is your trucks back window. You could go for a cheaper manual slider and the Reese is popular. There was a discussion earlier on the Anderson.
With the Pullrite you can either go with the Superglide, which is an under box mount, or with the "plain" Pullrite. Difference in price is significant. One of the issues that come with the Pullrite is their system is unique to Pullrite. Once your set up you will be only able to tow a fiver that has the Pullrite adapter plate and your trailer will only be able to be towed by a truck with a Pullrite hitch.
2013 Ram Longhorn 3500 Crew Cab 6.7 Turbo Diesel, Aisin Transmission.
2014 Jayco Eagle Premier 351 RSTS, Mor/Ryde Suspension and Pin Box, 17.5" wheel upgrade, 18k Pull Rite hitch.