In a 10 gallon, get a smaller species of pleco. It's much better to be understocked than near- or overstocked, and DPs have enough character that you won't get bored of the tank.
If you do set that up, make sure;
1) You have lots of driftwood, so the pleco(s) can hide and have something to chew on.
2) You have lots of plants, for the puffer(s) to build territory and for the pleco(s) to feel safe and secure.
3) A well-cycled tank with mature colonies of bacteria, and stable water parameters.
4) A good routine of keeping up with water changes and keeping parameters out of toxic levels.
5) Most importantly, time! Puffers, even smaller species like DPs, are a large undertaking. You can't simply throw the food in their tank and let them go, you need to slowly feed them, making sure to offer enough but not too much, to ensure the water doesn't become polluted. You also need to be able to devote the time for water changes and such.
Good luck! Keep us posted on your decisions.