I stop almost all RPO cheese to the slot WR by running Big Nickel Over G... my set up is shown below but I think you can run this from any of the coverage shells in that formation... and heck even in other Nickel formations (but I like BNOG because you can user gap shoot the run more easily). Just go into practice mode and try it out with your own playbook.
Coaching Adjustments - Autoflip ON; Base Align; Play Ball; Option Conservative; Hooks = 0 yards
Formation/Play: Big Nickel Over G - Cover 4 Quarters
Setup: Pinch DLine (Dpad Left LS Down; Slant DLine Out (Dpad Left RS up); Pass Commit (RB RS Up); Vert Hook your Slot CB (Y Y Y LS down)
Your slot CB will jump that RPO bubble pass almost every time for a pick 6... I like putting my best DB there. When I used the free Ramsey he sometimes dumbed out but Ed Reed or Kam or Sherman or Deion all seem to make the play... they all hesitate for a second and then pick the ball off EVERY time. Note for Gun Bunch TE and Single back Bunch TE... you have to manually bring your slot CB in towards the DLine but for all the others (like Trips TE) just leave him where he is.
The setups above are for the standard play. If they flip their offensive play, you have to flip your defense and make the corresponding adjustments because your slot CB may be a different icon. Otherwise it works the same way as unflipped. For the RPOs going to the outside WR... the only way I have stopped these is to use hard flats set to 0 yards and Pass Commit. But that leaves you open to other things.
Using this setup allows you to not worry about those pesky bubble throws. But you still have to worry about the runs... and powerful route combinations (like the deep crosser from Gun Bunch TE).