So I've got my 5 marquette bare roots ready to plant, but Im wondering about posts. Heres what soil reports for my community says: "Olive gray, cemented, very stony sandy loam till, derived mostly grom gray slate. Well to moderately well drained, class 5-7." Will pressure treated 6x6x10ft end posts, buried 3ft down be sufficient for 5 vines? I was also considering 36" mobile home anchors as well outside the posts for added tension.