Those are low pressure / low speed tires, around 13psi on mine. You should be able to plug the sidewall hole with a Slime rope plug right on the wheel, I should think. Sidewall patches work fine on low pressure tires with proper adhesive.
I like the Air-Loc tubes from Korea but the last two times I've ordered them from Amazon I've received another brand. Unless you have something to break the bead with I suggest you take the wheel and tire to the tire shop and have a tube installed. You might be able to plug a puncture but if it leaking through a crack like this you'll have to have a tube.