Katie, you had better put up a stake for a bird perch and if you already haven’t, cage that since it’s so low to the ground. Rabbits and clumsy shoes, and who knows what could damage your work. Birds believe it or not will land on those even how low they are.
One last thing you should know is that wind can easily blow out bark grafts. You’ve got a lot of root power and I expect those grafts to grow rapidly. A bird perch and stake double together to tie the growth to and to stop birds from landing on your scions.
Last year I grafted to a walnut at my neighbors and forgot I did it until months later on a similar size rootstock and several scions had grown 4-6 ft. and when I got back to it all were blown out from the wind. I’m still marveling how you were able to put those scions in there that low to the ground. 
Dax