I’d start ‘backwards’.
Start with a Step 2 or Second Step product by hand, with long, end to end of door saddle, front to back strokes.
If it’s obvious you need to go to a Step 1 – then make sure it’s well lubricated (mist it often with denatured water and/or some QD), backing off the lube until the results start to show up. Be VERY careful with the edges as they’re thin-skinned to begin with. I’ll sometimes use a dry sponge between my fingers and the applicator keeping only two fingers as pressure on the inner part of each “shelf� without any pressure along the outer edge. This lets the sponge distribute less pressure on the outer edge of the door jam. As you see results, switch to the next ‘shelf’ until it’s done, then repeat working your way back up the product ladder to the 3rd or final step in your detail procedure. This is not an area to look for perfection. There’s just not enough paint on those outer edges for you to exact perfection without possibly compromising the paint (and reputation).
Hope your fingers and arm(s) don’t wear out!
I always suggest exotics get clear-bra’s in the door sills once this is done. I’ll bet the passenger side is filled with deeper scars and marring from women’s heels dragging across them ... they never want to lift their legs and feet so high as the valet-guy can look up their skirts. Any ‘low-riding’ sled has these scars on the passenger side from this very reason. Once we explain how and why this is happening – then show them how much worse the passenger side is (it usually becomes a humorous enlightenment for the owner) ... we can charge a LOT of money to detail it, and I usually triple whatever the ‘clear-bra’ companies charge is for this area.
Good luck.