To be honest, it doesn't seem like you've actually confirmed you really need lower gearing. I'd go and try riding the stuff you've got planned, and adjust as necessary. Swapping out a cassette and RD doesn't take that long. That said, while I haven't tried it, an 11-36 is likely quite a stretch for your rear derailleur, both in terms of cog size and range. SRAM officially supports up to an 11-32, which means that you can probably make an 11-34 work. However, a pleasant quirk of SRAM is that you can use a 10 speed SRAM mountain RD with your drivetrain (or 11sp road). SRAM did change their cable ratio for 11sp mountain.

There are absolutely lots of cases to want lower gearing than a 34/32, but for unladen riding of non-super-long distances on paved roads, that should work pretty well for most fit cyclists, as extended extremely steep pitches are discouraged by road engineers. That said, having low gears is certainly very nice.