I think this is a wonderful idea! Because they are such a diverse group with many different life histories, there are likely many methods to finding and observing beetles. My suggestion is to look at similar methodologies for other taxa and adapt them for your purposes.
I know many beetle species can be attracted with UV lights at night, similar to moths. There has been some discussion about the ethics of this, including here on the iNatForum (see here and here).
Additionally, many beetles can be found under rocks and logs, similar to salamanders. Herpetological societies often have ethical guidelines that could easily be adapted for your needs (see here).