Tubeless with liquid or inner tubes with liquid?
In your case I would go with tubes. The Tubeless evolution comes from the advantages you list and some disadvantages. 

The only one that is of interest to you is puncture resistance. By putting slime in tubes, you gain that without most of the the disadvantages of tubeless. 

As the slime dries is needs topping up, if using tubes and neglecting this maintenance won't induce a leak as can happen with tubeless. 

You will need to source tubes with removable cores in there valve. This not only allows you to insert the slime (without puncturing the tube), it allows you remove the vales when it gets gummed up by slime for cleaning or replacement. 

To be clear, the disadvantages of tubeless over slime filled tubes are small - initial seating of the tire and burping. You probably won't have a problem with burping as you won't be running low pressures over rough ground, so really once the tires are mounted, there is not all that much difference in it.