Ideally you would want four or more radials for each band extending out horizontally. Any antenna intended to be mounted on an HT has performance that is greatly compromised in favor of convenience. It's hard to say what method would work best to improve such an antenna. My advice would be to experiment. Your idea sounds like a reasonable thing to try; just keep in mind that the elevated (i.e. not ground-mounted) radials will be part of the antenna and will radiate, so use insulated wire and tape over the ends so they are insulated too. I'd suggest over-the-air testing of antenna "A" versus antennas "B" and "C" to see whether your idea works better than the same antenna directly attached to the HT, and better than a shorter, more convenient antenna.
Whether or not going to all this trouble is worthwhile depends on your intended scenario. If your plan is to hike around a valley dominated by a massive mountain with a repeater on top, then it's probably not worth the trouble, because any old antenna would work fine. In my rural area, hiking with an HT is a very good idea, because one can contact a repeater many kilometers outside of cell phone coverage. In one famous case, a family was lost and stranded in their station wagon for over a week, and the husband and father died of hypothermia after he left on foot to find help; if they had had an HT, they could have easily contacted civilization.
For emergencies I carry a dual-band J-pole antenna along with my HT when I'm hiking. A dual-band J-pole is the gold standard for HT antennas. Its downside is that one can't walk around with the antenna connected to the HT, because the antenna is long and floppy; one throws a cord over a branch of a tree, ties it to the antenna, and pulls the antenna up. The antenna was designed by Ed Fong WB6IQN, who published an article about the antenna in QST magazine. Ed also sells the antennas very reasonably on a popular auction site.
