The way to deal with potential splitting between bolts is to make one of the bolt holes a 'slotted' hole, ie. oversized.

There are two types of moisture meters, electrical resistance meters and capacitance meters. The type of meter that's best for you will depend on what you want to use it for. Resistance meters are more accurate but are slower to use since they involve driving pins into each sample to obtain a reading. A hammer electrode would be needed to test hardwoods and will be equipped with two insulated pins. Each test leaves two pinholes in the wood. Since the electrical resistance of different species varies, corrections need to be applied to the meter readings.

The electrical conductivity/resistivity of wood varies according to species, but also to several other factors.

There are engineered timber structures built in the 1950's that are still in use, and a couple can be found here https://historyandheritage.cityofparramatta.nsw.gov.au/blog/2020/02/05/wentworth-point-a-brief-history and here https://www.westconnex.com.au/media/aunllvd3/new-m5-rudders-bond-store-archival-recording-september-2016.pdf.