Topband: Inverted L capacity hat

[Szegedy]

Dear Friends!

I like to make a inverted L for 160m.I have limited space.
I live in a block of flat in the inner city, the house is 30m high, houseroof is only 20x26m.
The vertical part of inverted L will be 18m.
My question:
1.Which is better efficiency?Using only 1 top wire(22m) in horizontal or 1 top wire sloping down a little(about 20m) or using 4 top wire(each is 17m) sloping down at 45 degree?
2.If I use 4 top wire ,antenna will radiate 4 direction?  Normal inverted  L radiates only one direction? Lot of difference or not? 
3.I have limited space for radial,no space for 1/4 wave radial ,I have only 15m(45 foot) for each direction?
   Anybody tried to use trap radial? To use a coil or capacitor in each radial? Or not?

                                                                             Thanks :Laszlo