We could do it, but it's kinda ghoulish from the POV of others, don't you think? This is one of those things where you need to know the beliefs and cultural practices of your target audience.
I wouldn't be opposed to it, though, so long as they are used sensibly. Write something up and I'll help polish it before running it by DP.
It's only meant to gather the bodies of enemy combatants unless otherwise specified, and while it technically swallow them, it's not eating them, it's putting them in a storage place for later retrieval, so I don't see many of our allies being against them.
The Githzerai might not want them gathering their own dead, but I don't think they would have anything against, them gathering the bodies of the Illithid and their slaves.
But I unfortunately still don't know how to design a creature, I can come up with ideas for what creatures to design, but I don't know how to design them.
I do think a Small Viper would make an excellent base to design the creature on, it's a CR½ 1HD creature, that's basically built to stay hidden, and move quickly across difficult terrain, all it need is to be converted to a plant creature, and have Shrink item and Hoard gullet abilities added to itself, and you have a very cheap creature, that can gather corpses for us, with how cheap they are, we don't even have to add more than rudimentary anti-far realm measures on them, because it's no big deal, if one of them occasionally mutate a bit.
A Tiny Viper would be even better, they have a higher hide check, and if the corpse gatherers are discovered they're dead whether they have 1HD or ¼HD, but I'm not sure if a ¼HD base creature, can have 2 spell like abilities.
Add slightly bigger snakes to gather magical items(since without being able to shrink them, some magic items will be too big for the small snakes) and we have an effective means of looting the battlefield.
They will of course have to be trained to know how to retreat, but we can just train them to do that, at the sound of a horn signalling retreat, or for when they're part of a stealth mission, we can have them retreat when they smell a certain smell, released by something their handler carries.
But really I don't think we will run into much in the way of cultural problems, sure it's slightly ghoulish to have corpses swallowed by snakes, but I think most people will still prefer to have their corpse recovered, instead of left on the battlefield to rot or be used by the enemy, it's not like the snakes deliver the corpses right to the Forge, they simply retrieve them from the battlefield, our allies still get to decide what happen to them from thereon.
