[FT] Large Scale Ship Defenses

I'd be curious to hear from anyone who has made rules/situations where
'Large Scale' defenses are brought into play.... For example:

1) A space station that projects a shield that protects friendly ships within
6 MU 2) A ship system that can project a shield that protects friendly ships
within 6 MU (Sort of like an ADFC for shields.) 3) Planetary Based ECM that
reduces enemy range bands by 50% 4) A nebula that reduces range bands for all
ships without 'hardened' systems 5) A nebula with explosive gases that
detonate if too high of a thrust rating is applied at one time.

There's lots of other ideas.... I'm just curious how many people use special
situations in their games, and how well they come off.

Also, would be curious what people would think about a ship system as
described in #2. Viable system if mass factor can be assigned?

Just some things to think about..... If this has been discussed before,
then nevermind....  ;-)