I handle my hot items a few different ways:
1) Welding gloves for large or heavy items such as cast trays, grates or smoke cans boxes;
2) I have several different styles of tongs designed for food handling that I reserve for handling live coals, smaller smoke cans/boxes such as in the GOSM, or anything smaller and light enough to get a solid grab for stable control of the item. I've often used two tongs to lift out a charcoal grate while loaded, to transfer the hot coals to another cooker. A larger (10-12" or larger) channel-lock pliers would be a good tool for handling a smoke box, just keep the exposure to heat from the smoke chamber brief so the handle grips/metal tempering aren't damaged.
I always wear a pair of welding gloves when tending a hot smoker, or handling charcoal chimneys, but I prefer to use tongs for handling anything hot when it's safe to do so. Leather begins to break-down from high heat exposure over time, and will compress, offering less thermal protection. The interior insulation is part of the protection, but the leather is your first line of defense for your hands, IMO.
If you have a local hardware store which sells welding supplies for the backyard tinkerer, they are generally the least expensive source overall for welder's gloves. Specialty welding supply outlets will have them as well, but prices are usually much higher for similar quality and brands. Certain department stores will carry them also at very reasonable prices.