Dear tropical fruit forum community, I am hoping to hear some advice as I am total new to gardening and this avocado tree is too precious to us. It's 25' tall with grafted variety on right side and rootstock on left side. We are contemplating to trim the tree down to more manageable size, the questions are:
1) In SoCal zone 10b, how risky is topping? It may involve 4-5' topping on the main rootstock branch (#2). We want to find the balance between easier picking and long-term damage. Minimal yield for couple years is expected.
2) The rootstock side may completely lose a major branch (#4), cut at approximately 5 feet from the ground, roughly 1 feet diameter. How realistic is it to graft a piece of scion from the "good side" to here? Grafting tutorials seem to talk about significantly smaller bark diameter (within 1/2 feet). Is it too much for the tree's health to trim and immediately graft?
3) There is a lot of weight on the good side branch, what would you recommend for a good support? Maybe put a 4x4 wood underneath?
Your help is greatly appreciated!
Edited to add photos of trunk damage