I don't profess to know everything, but since your dog is a puppy, even though crating is not ideal for that long, it would be much, much safer for your dog. You can get one of the wire crates, and you can get one that is a little bigger than he would need as an adult dog to give him a little more space. x-pens are also a good option, but crates are nice because they can't jump over them and can't wreck what is underneath them.
Also keep in mind that you may need to use the crate in the future, even after puppy has earned the right to be loose in your house. Having a crate open in the house all the time gives him a safe place to rest, provides security when there are major changes in his world (such as next year when you plan to purchase a home), and they are great for traveling too (and the wire crates collapse to store flat, very easy for travel).
Crates aren't super cheap, but when you consider a) the price of keeping a pet and b) what it will cost you to replace everything he destroys, the cost of a crate is nothing.
You may also have a dog walking service in your town for a decent price, I would look into that.