Set Temp Dehydrator

If it has a fan then it is quite usable – you just need to keep an eye on your items. Most likely you will need to move the trays around during the drying to make sure everything is evenly dried.
You will also need to check more often if drying veggies/fruit so you don't over dry them.

Yep, its got a fan. And the trays rotate very easily. This is the model. It isn’t great, but it was free. Now that I have specified the model, will I be okay dehydrating things like pasta dishes? I mainly want to make meals for backpacking, but only if it’ll be safe.

I'd just be careful with the layers – keep everything small and uniform, thin layers so it dries faster (this brand isn't the fastest for drying). Also, try to dry on lower humidity days as well.

Otherwise you should be just fine!

My main concern is for things like chicken and beef. There are some good places that I can find out how to dehydrate them, but with a set temp of 150, I might not be able to follow the directions exactly. For example, many places that I've read call for ground beef to be dried at 155 deg(F). I know 150 would take longer, but is there any safty risk with the loss of 5 deg(F)?

Not a real issue at 5* difference – but again, it will pay off if you check the food every hour and stir, to make sure all sides are being evenly dried. And keep the food small if it is meat to dry faster. That will speed up the drying process.