Ken, I was pretty much in a similar situation, around gfr 13/14 we went hiking to quite a few places - the arches national park + New Zealand + great barrier reef... I still feel that it is possible to get some mileage from your kidney at those gfr numbers as long as diet comprises of soluble protein, (like vege/fruit/lentil) genetics plays 70% role approx 30% is diet related. Non soluble protein in diet will damage the kidney nephron filters eventually or rapidly depending the state they are in.
I sense you on the right path. ( I am no authority... ) & wish you the very best. ( btw: my wife was the donor ... which I think was a miracle.. which I still cannot get over (its nearing 4 years). You should also consider multi listing once in UNOS database. You may like to visit srtr.org that gives you an insight into the kidney xplant outcomes nationally.
Best