I use my beloved AL Titan Lx as my singles reg and it has only one HP port. I also wanted to put a transmitter on it but wanted a backup SPG since I don't really trust my hoseless computer. Short answer, I got an HP splitter from a local LDS and it works just fine.
Do I get snickers from some of my DIR friends? (Well, much of what I do draws snickers....) But, so what. Is there "another failure point?" Of course. Has it failed? Nope. What if it does? Well, the quick answer is the dive ends (eventually, it is a HP failure point afterall). And then all you do is take the splitter off, plug in the SPG hose and use your hoseless AI computer as a NON-integrated computer -- trip saved and that takes maybe 5 minutes.
It is a very easy way to go.