This entire post reads "I don't know how to camp/go backpacking.
Get yourself a travel air mattress or sleeping pad, probably a better sleeping bag. Solves the lack of sleep and sore back.
Get a proper tent that's water proof and learn how to set it up properly so water doesn't pool under it. Make sure the vents have good mosquito netting to keep bugs our, and never have the entry unzipped a second longer than it takes to get in and out of.
For the mice, don't have food in unsealed containers and if you're in bear country you should be hanging a bear bag at least 100 feet (30m~ ) from you campsite, make sure cook wear and utensils are all properly cleaned too. Some newer tents even have a pouch built in near the door to seal a bag into, minimizing the chance of something deciding to make it a new home.