I have become a convert to rail clamps. Great to keep track formations in correct geometric shape and stops things getting hammered apart when the terrain ain't level and you have heavy locos. As well as helping maintain electrical conductivity.
Couple of points -
1)Take care to make sure you are not trying to clamp over the plastic tabs on the edges of the sleepers that can be hidden under the rail, rather than just the rail profile or over the fishplate only .
2) Do not rely on a clamp, or tapped screw connection on Aristocraft track, alone to ensure long term electrical conductivity on an outdoor layout. Make sure you pop a bit of LGB graphite paste or "Coppergrease" on threads or connecting surfaces to protect against surface corrosion/oxidisation. Trust me. The 6 P's as they say - "P**s Poor Preparation leads to P**s Poor Performance.
Max.