Usually the equipment is a transceiver, tuner and antenna. Nice to have is a Pactor modem if you want to do email over the air from your boat. I too have a split backstay. I used the Gam antenna and it worked fine. I had a problem with the feed line so I'm going to a backstay antenna. If your lower leg of your backstay is longer than 20 feet, then it should be ok. I'm personally removing the split and going with two separate lines. Bottom line is most of the mast support is done by the forestay and shrouds. As long as you inspect your backstay, it should be fine strengthwise.
If you don't want to do these options, you can use a whip antenna.