I have never had a problem cooking a loin low and slow. I would inject it first with some apple juice and a bit of the rub you are going to use. This will keep it moist thru the cook, don't forget to baste, or mop. Try this rub, it is simple but damn good.
Quarter Cup Brown Sugar
2 Tbsp. Paprika
1.5 Tbsp. Kosher Salt (dissolves better, and is not as salty as table salt)
1 Tbsp. Garlic Powder
1 Tbsp. Onion Powder
1 tsp. Crushed Red Pepper Flake
.5 tsp. Chilli Powder
.5 tsp. Red Pepper Powder
Just mix all together then run onto loin.
You may want to use my mop for this too. I use it normally for my ribs but works for all pork.
Here is the mop (sop, whaterver,)
In a medium sauce pan add the following ingredients on a medium heat.
12oz bottle Samuel Adams, or other High Quality Beer
1c. Apple Juice, or Cider
1/4c. Soy Sauce
4TBSP Worcestershire
1/2c. packed brown sugar
3TBSP Garlic Powder
3TBSP Onion Powder
1TBSP Crusher Red Pepper Flake
1TBSP Red Pepper Powder
1TBSP Chilli Powder
1TBSP Tabasco Sauce
1/2tsp Paprika
1tsp Kosher, or Sea Salt
Let this come to a soft boil, then reduce and simmer for about 10 minutes.
After that it is all ready for you to mop those Rib Bones.... It did turn out pretty good, adds a sweet kick.
Try it out, everyone that has had it really likes it.