Have you tried the compressed rawhide…where it is rolled really flat, and then compressed back together, and cut into shapes. It is usually dark tan, instead of white. And while a dog could still choke on those, they tend to come apart in smaller, more digestable 'sheets' instead of chunks. It is the only kind of rawhide I will use, and I have never had a problem with it. I do take it away when it is 2-3 inches. Some dogs will consume a 12inch bone quickly, some will work on it for weeks.
Also consider that this might be a behavioral thing. A lot of times, a dog is engaging in resource guarding when they gulp food or treats down un-chewed, particularly if they feel like someone is about to take it. The fact that the blanket fell on him, and startled him, then he squawked, then he swallowed the chunk (or tried) makes me think he might be doing some resource guarding. You might see about doing some treat exchanges with his favorite things, to make sure he doesn't panic if he thinks someone might take something from him