Updated - Solo Wukong - Season 5

You need Warrior Tabi ASAP (after Warrior's Blessing ofc.)
Other than that it is fine, but you should think about Stone of Gaia and Gladiator's Shield.

Your build looks solid for the most part. The solo laner should split responsibilities with the support. So instead of Bulwark of Hope, Pestilence may be a better option. I like your idea of Mystical Mail. But again, you may need to split responsibilities with the support. Better options could be Midgardian Mail or Void Shield. In My opinion, you don't have enough power to make use of Titan's Bane (it also doesn't give pen against objectives anymore- someone correct me if I'm wrong).

Mystical Mail is not good to get as late as Sixth item, where magical protection from either item's or scaling will render it useless. It's more of a second or third item in a build. Shifter's Shield is not a bad item on Sun Wukong but it's better on assassins/junglers (although it does work decent with his passive). Hide of the Nemean Lion is good, Bulwark of Hope is... ok but you will likely need Pestilence instead most of the time. Hide of the Urchin is situationally good.

Now, Titan's Bane should not be built on Sun Wukong, why? because Void Shield exists. If you need penetration, then Void Shield is a better item as it not only increases your damage to squishy enemies like the ADC and Mid through the protection reduction, but increase your tankiness as well, unlike Titan's Bane.

A build I would suggest instead against a physical opponent in lane:

Example Start: Warrior's Blessing, Breastplate, Chalice of Healing. (An alternative would be forgetting the Breastplate and getting some Healing Potion or Multi Potion).

Example full Build: Breastplate of Valor, Warrior Tabi, Stone of Gaia, Pestilence, Spirit Robe, Void Shield.

This is an example build, specifically against a physical oppponent in lane and as such shouldn't always be followed. Item's like Breastplate of Valor can be swapped for Hide of the Nemean Lion, Spirit Robe can be swapped for Hide of the Urchin or Mantle of Discord. Stone of Gaia can be swapped for Gladiator's Shield (Gladiators should be sold lategame) or Winged Blade (if Enemy Jungler is Nemesis). Midgardian Mail and Witchblade are also quite good now. Ancile and Runic Shield can also have their uses against a fed enemy mid or a magical opponent in solo.

Even Warrior Tabi can be possibly sold lategame for either Reinforced Greaves or another movement speed item (if you already have one), for example Winged Blade (Not 100% necessary due to his ult and slow immunity on Eagle and Ox forms) and Masamune, or Witchblade and Relic Dagger. I don't think Stone Cutting Sword is as decent on Sun Wukong as it is on Osiris though.

Listing Relic choices can also be helpful, they typically are: Heavenly Wings, Magic Shell, Shield of Thorns, Horrific Emblem, Teleport Glyph. Rarely will you need relics such as Cursed Ankh and Phantom Veil.