When I'm traveling, if I can't find a free dump and fill station, I just bite the bullet and find a cheap RV park, pull in for the night, plug in grab a long hot shower, dump, fill, recharge batteries, do laundry, etc. Costs more than just paying for a dump, but I get a lot more.
Unfortunately, I'm not sure how many RV Parks are accepting new guests. If you are heading west check out Dream Catcher RV Park in Deming, $20/ nite for Escapee members, $25/ nite for non-members. If not staying there the dump fee is $2.50-$5.00. Call ahead to make sure they are taking people during the pandemic.
Phone # (575) 544-4004
Good luck