I kept a doface puffer with a Hawaiian spotted toby and a leopard toby and they never had a problem. There was a lion and a marine betta in the tank. I never had a problem with any aggression of fin nipping. This was my experience, only. I don't know if it holds up as a generalization.
If you can wait on the puffer (will they hold it for you?) I'd add the lion first. It may not make a difference either way. If the puffer is peaceful, I expect he'd leave it alone, if he is naughty by nature, he'd probably harass it anyway.
FWIW I have kept many puffer species including several dogface puffers over many decades of fishkeeping. They have always been the most peaceful.
If you are going to get a toby, I'd recommend the aiptasia eating filefish, since a saddle puffer mimic may look too much like a toby for your taste.
If you can wait on the puffer (will they hold it for you?) I'd add the lion first. It may not make a difference either way. If the puffer is peaceful, I expect he'd leave it alone, if he is naughty by nature, he'd probably harass it anyway.
FWIW I have kept many puffer species including several dogface puffers over many decades of fishkeeping. They have always been the most peaceful.
If you are going to get a toby, I'd recommend the aiptasia eating filefish, since a saddle puffer mimic may look too much like a toby for your taste.