I was facing a simialr problem as well. I ended up buying dry plate holders on ebay for modern camera (thickness). Oddly enough my 8X10 is an Imerial View Camera from 1903. Those dry plate holders SUCK! They are way too difficult to "safely" load your glass. Some of the holders have metal clasps that will severly contaminate your wetplates as well.

I was given a GREAT book. Primitive Photography "A guide to making cameras, lenses, and Calotypes." By Alan Greene. This book has detailed info on making holders for use in modern cameras. It is a different process but if you convert his wet paper process holder (the paper is sandwitched between 2 sheets of glass) it is not too much modification to convert it to wet plate, and it will be easier to load them into the holder. The materials are around 35.00 to 40.00 USD. I found it well worth it.