Trailer Tires Question

I've been working on the trailers that my sons High School Marching Band uses to get to their different Field Show Competitions. Some of the tires are looking really old, but are still holding air - but two are getting replaced on one of the trailers. It's a enclosed 6x10 trailer - so there isn't that much weight involved. Because these trailers are used less than a dozen times a year, should I look at getting tube tires or tubeless? With a tube tire, we would only have to replace the outside rubber as it cracks with age, but the innertube would still be good. Or should I just go with a tubeless radial tire? Let me know your thoughts.
Thanks!