As someone involved with UTM and QEMU… use UTM 4.0.x or even earlier if you want stability; QEMU 8 seems to have some issues, and UTM inherited them with the update. Osy reverted to QEMU 7 to try and fix this, but that only solved some of the issues.
If it’s for work and they’ll pay for it, it might be worth using Parallels until UTM is stable, or keep regular backups of your images so you can revert if UTM/QEMU hoses your current image.
It’s worth noting that UTM can use sparse qcow2 images, but can also use compression on them which can help free up space.
UTM can also run images from an external drive now, so you could get one of those tiny 512GB thumb drives and run everything from there.