Hi Tim
To reduce nasal congestion, maybe the first thing is to investigate the cause: I am not an expert in diet but too much dairy can cause phlegm to accumulate;
post nasal drip can also be diet related. Try finding a diet that reduces or eliminates the nasal congestion. When you do have it, another option is
neti to remove the buildup. You can practice neti before your asana practice. If you still have it when you are doing asana, then it may be practical to not let your head drop forward, so supporting your head on your hands or a bolster may be good, as you are already doing. But another approach is to seek out that congestion, because it will assist in moving the phlegm around. Inversions are often recommended as a way to reduce the congestion by turning everything upside down. (See this post on
GaiamTV.) So, maybe we should not be trying to reduce the symptoms, but rather finding the cause, changing what needs to be changed and then work through the remaining congestion (neti or inversions) to reduce it.
Cheers
Bernie