Green beans roast decentlyl.. toss them with some oil and salt and pepper and maybe a little shallot or herbs and roast them at 350 until they're soft. It'll probably take a little while.
You can also pre-steam them in batches and hold them to speed up the roasting process.
Same goes for the corn, roasting should work fine, as would the grill.
another possibility for the corn is to borrow a big turkey fryer from someone and boiling them in that.