I would like to rebuild a railing on an existing deck using 4x4 posts. I want a 42" railing and privacy lattace of 42" above the railing. I plan on using a 8' 4x4 post. My rim joist is (2) 2x10. Will the rim joist be able to support the 8' high 4x4 post? I plan on attaching the post to the rim joist with carriage bolts. Neil