Pick a new field as you aint making your chosen one..
One of the many wisdoms passed to me repeatedly over the decades has been: Once you have a plan in an emergency, don't change it unless there is no choice. This goes extra for forced approaches. Aside from allowing yourself several different landing sites which are all very close to each other, you're better to make the right decision first, and stick with it. Changing your mind while gliding down certainly wastes altitude, and invites a poor outcome. If there is an adequate landing site close, it's a better choice than the perfect looking one farther along. 'Same logic as not flying past a fuel stop, 'cause you think you can make it.
While enroute, you should be constantly considering where you might force land if the engine quit in the next minute. Perhaps the site is one you just flew over, and had a decent look. The one you've flown over and seen from several angles, is certainly better known to you than the one which is still ahead. You can't judge its suitability and distance as well. If the engine quits, you're no longer trying to get further along your route, you're just trying to get down safely. Making the best decision first, and sticking with it is an important element of things not getting much worse mid emergency. If you're really unsure about the suitability of the forced approach sites in your area, fly higher, to give yourself more time to select, and glide.