I'm certainly not the most experienced WC practitioner here, nor do I have a lot of sparring experience. But I have just enough to know what works for me.
I think that you might be chasing the hands too much. Don't think about "bridging." Bridging is something that happens, not something that you make happen. If you go in with the idea that you're going to bridge with some technique on his arms, you're likely to find his hands no longer there and hitting you elsewhere when you enter. The key is to always chase the man, not his hands. When he punches, just punch back on a better line, and if contact is made, that is where your chisau may come into play. Chisau teaches us to go around or remove obstructions with the intent of chasing center -- hitting the target. That should be your only goal.
At least, that mindset works for me. I find that I always do much better when I focus on chasing center and don't worry about the other person's hands. The techniques and attributes that you develop in chisau practice should come out automatically when you need them.
Also, keep in mind that if you don't practice entering and closing the distance, you won't be able to. So staying out of range and using Wing Chun isn't a smart move -- it's just depriving yourself of developing an important skill and learning to apply your Wing Chun effectively.
