>>1793440A small tent does not sound like a bad idea. Use the zippers to create a seal. And then seal around that with tape. And then flood in some gas from one of those BBQ gas canisters. I even have a hose attached to mine for the BBQ. Couple campers have actually died while pic related inside their tent.
Or you know. You could make it easy and just throw a big BBQ gas canisters onto the animal and kill it. Just think of it as squishing a bug