Spectrum is a precious resource and designing a system/implementation with deliberate intent/need for re-transmission if frankly anti-social IMHO! 
Better to use a more robust mechanism in the first place - as highlighted the cost of a full LORaWAN GW isnt much more and if using it for e.g. TTN then has social benefit in being part of an open deployment…remember ALL your TX & Re-TX will be ‘seen’ by other local LoRa users and will act as potential increase in traffic and raise noise floor…you may be in a remote location not impacting others then get away with it but it doesn’t scale (what if a friend living in an urban environment with other LORa/LORaWWAN systems around ‘likes’ your implementation and wants to replicate?) and posted as a caution to others thinking the same…just my 2 penneth worth! :_)
Single channel GW’s also ‘look’ like std GW’s and may confuse users or potential deployers whilst only serving to cause lost packets and confusion - not a great help when debugging a deployment…a wider question to TTN Forumites in general: dare I suggest a personal view that TTN has matured enough that single channel GW’s should be blocked as causing more trouble than they are worth (note deliberately provoking debate on this vs playing a Troll! - may be worth having a discussion thread to canvas opinions as beyond just this device topic?). When GW’s cost >£1k there was excuse for development and experimentation but with wide availability of <£300 & even several now <£100/150 GW’s do we need to move on and reset limits for use?