Bear in mind that Yuzu is not resistant to phytophthora root rot whereas PT is.
For instance the highest yield,fast growth rate and sweetest for satsumas mandarins is Rusk citrange. Yuzu gives the half of that and makes it less sweet.
Another promising rootstock and very fast growing, resistant to tristeza virus, but not resistant to cold weather is Shiikuwasha. This rootstock continues to grow in winter compared to PT and its hybrids because it has the lowest concentration of growth retard hormones.
Also this rootstock is used to induce flowering in hybrid seedlings, like one third flower in 2 years and a half.
I have a Shiikuwasha which just made fruits and will probably have seeds in winter/spring if you are interested.