How to properly implement Bluetooth modules?

[SolarSunrise]

I've read from multiple sources that bluetooth antenna would get detuned if covered by a plastic enclosure. My question is, how do I properly use a bluetooth module in my project (RN42 or SPBT2632C1A.AT2) with a plastic case? In my case, the communication requires a very fast baud rate (~500k) along with a very stable connection (very few packet losses). So how do I solve this issue without using  a network analyzer  or running a complicated simulation? Or am I being too paranoid about these kind of things for a one-off project?

Thank you in advance!