Is there a setup where I can leave the water on all summer?
There's really not much that can fail in a setup like that if you use quality components. A hose bib on a post or standpipe used to be a common sight in gardens before underground irrigation became so common. 



Even with old rubber hoses disaster rarely struck. Modern reinforced hoses make failure a very remote possibility that shouldn't dissuade you from following your plan. 

Run a good hose from the faucet and install whatever valve or hose bib that suits the good lady's needs.