I'd recommend tire liners if you can get them to lay correctly in the tire AND add Slime. Another user says the trick for the tire liners is to partially inflate the tube and tape the liner to it and then place them both in the tire and complete the mounting process. I haven't tried it, but I would probably recommend using something like painters tape and lightly tape it into place on the tube. Once mounted, as you increase the pressure in the tube, the painters tape should release on its own due to its low adhesion.
As for Slime, it recently saved my butt on 2 occasions within the same week on my 2018 RadRover. The first time it completely plugged a small hole probably from a kiawe thorn and I only lost 6 PSI. A few days later I had a small gash, which I think was due to a glass shard. Slime slowed the air loss so I could finish my commute to work only having to stop once to air up. Once I got to work I made the necessary repairs. Slime is easily rinsed off with water so no worries about it making a mess inside of the tire. Enjoy your RadRover!
I think every little bit helps, so go with the tire liners. I've had mixed results with sealant in tubes. The few times I've had punctures with sealant, the debris that punctured the tube was way too much for the sealant to handle and left a huge mess.