The third pillar of the Standard format, despite being on a steep decline, is W/R. The Vehicles shell is strong, even if it has been outclassed by G/B and U/W decks. So perhaps the answer isn’t trying to go under them with aggressive creatures like Scrapheap Scrounger, but to instead go a bit bigger.
W/R Midrange still has the pillars of every white deck. The full playset of Smuggler's Copter and Thraben Inspector is a no-brainer, providing an early creature that will replace itself with a card and can crew the powerful Smuggler's Copter.
There are no Toolcraft Exemplars, however. This guy has been getting outclassed and requires a minimum number of artifacts to be effective. When Scrapheap Scrounger can’t block and you’re not interested in the slightly underpowered Pia Nalaar, you can drop this guy entirely.
Veteran Motorist sticks around as an efficient early creature that also provides advantage late. Scry 2 is on a similar power level to drawing a card, and being able to pump a Smuggler's Copter later in the game is of additional value. This is also the only creature in the deck that is susceptible to Liliana, the Last Hope killing it, so you aren’t playing the full amount. With only 3 Motorists and no Exemplars or Selfless Spirits, you are much stronger against her than the average Vehicles build.
The 3-drop of choice is perfect for a midrange shell. Fairgrounds Warden is an excellent tempo play that can take out a threat on the battlefield while still making sure that Smuggler's Copter is ready to attack. This is not the best creature in the world to use Reflector Mage on, so that’s a nice benefit.
This deck utilizes a pretty full Angel package. There are multiple Gisela, the Broken Blades and Archangel Avacyns, and then a Bruna, the Fading Light to top things off. These are great cards when you’re extending the game. Both Gisela and Archangel Avacyn are susceptible to Grasp of Darkness and potentially Harnessed Lightning, but Bruna makes sure that isn’t back-breaking. Linvala, the Preserver can bring you back from very far behind. Against an opposing Ishkanah making a bunch of small creatures, Linvala can make some large ones.
Thalia’s Lancers glue the Angel package together, letting you search up any of the various Angels you want, attached to a 4/4 first strike for just 5 mana. This also gives you some reach in deck building. You can add a single Geier Reach Sanitarium so you can fetch a land when needed, as well as a Skysovereign, Consul Flagship.
Gideon, Ally of Zendikar isn’t the planeswalker of choice in this midrange deck. Instead, there are 4 copies of Nahiri, the Harbinger. Nahiri, the Harbinger can come down and take out a powerful opposing creature, such as Spell Queller or Grim Flayer. It can also kill a tapped Smuggler's Copter. You can loot away excess lands or Angels to bring back, get rid of extra removal spells, and the ultimate is a huge threat in a deck with Thalia’s Lancers and all these Angels to take over the game. You won’t get the cast trigger on a Bruna, but you can meld her or simply bounce her back to your hand for value on a following turn.
R/W Midrange is a different approach to an established strategy, with a power level high enough to rule the skies of Standard going forward.