When planted in containers, they can be grown with a trellis or allowed to trail over the sides of the container creating mounds of deep green foliage covered with blooms.

The ideal would be to spaced them 2 to 4 inches apart..

Are you the type to pay attention almost daily? If so, I'd leave them all, weaving them intricately, so there's not a ton of bare space at the bottom that is so common to vine-growing. Vines are made to deal with cramped conditions and self-tangling. With that much material, you can make a beautiful, solid covering, guiding them sideways often. They would tend to go straight up if left alone, creating a tangled mass at the top of bare-ness.

This pic is from 2 or 3 years ago, but MG's are MG's. (Still pulling the sprouts from the seeds these dropped, but they were pretty that year.)

They are looking fine. If it gets too crowded you can selectively thin out vines or take a scissors and prune foliage if it gets out of hand.