The best replacement for flaps is spoilers.

The best alternatives to flaps are rated as following:
★★★★★  spoilers
★★★★  splash guards
★★★★  ailerons
★★★  flaperons
★★★  slats
★  mud guards
★  fender flares
★  no mud flaps
★  grafts
  aileron
  stall speed

Your alternative for flaps is not listed? Suggest!
Speaking about flaps, one probably shouldn't forget about fender flares.

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



Google Trends

Scale is based on the average worldwide traffic of flaps in all years. Click on graph for more.
flaps
spoilers
splash guards