This topic has been brought up before but I'd just like to state once again that current system for destroying mine supports sucks.
Once an area is mined out it would be nice to be able to place things inside of it with less restriction from the annoying supports that get in the way but it's impossible to destroy them all.
Perhaps we might be able to place some sort of mine brace that can be built and extended a fair amount of distance. The two points where you start building and where you end building would be posts like any normal support however the extended portion would be above the player attached to the ceiling to allow for walking underneath. Preferably this portion would not even be visible except for a support radius which indicates an area you've mined out is now supported and its safe to destroy any supports within that radius.
The brace isn't for mining and would not work in that way, only for destroying the supports in safety afterwards.