It is a commercial engine that has been out of production for years so there is little interest for the aftermarket to provide a conversion. It is not really difficult to change as the canister has a drain. It is more difficult to change the secondary fuel filter on the front of the engine and even more fun to get to the grease fitting on the water pump. It's just part of owning a classic Airstream moho with an Isuzu.
If these maintenance jobs concern you, never ever look under the dash.