water wand with tank -- 1gal, 2 gal 3 gallon options out there. you pump it, point the wand, and press the trigger.
find a better place for the tent that gives you access to 3 sides. make sure the tent wall you can't unzip is along whatever wall you place the tent by.
or, automate the irrigation.. with only 4 plants it's nice but not a huge benefit unless you need it for vacations and such when you are not at home.