The best replacement for trailers is panniers.

The best alternatives to trailers are rated as following:
★★★★★  panniers
★★★★★  fifth wheels
★★★  mobile homes
★★★  5th wheels
★★★  campers
★★  roller trailers
★★  fifth wheel
★★  travel trailers
★★  bumper pull
★  junowallet
★  motor homes
★  5th wheel
★  haulers
★  previews
★  fifth wheel trailers
★  containers
★  wells cargo
★  trucks
★  rvs
★  motorhomes
★  bunk trailers
  clips
  seats
  bike seats
  houses
  big tex
  park models
  straight load
  steel horse trailers
  modular homes

Your alternative for trailers is not listed? Suggest!
Speaking about trailers, one probably shouldn't forget about hitch.

Other search terms related to trailers and their ratings are:
★★★★★ hitch
You have in mind a companion for trailers and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of trailers in all years. Click on graph for more.
trailers
panniers
fifth wheels