For what it's worth I have both a level kit and bags installed on my Tundra. For the level kit you have 2 ways. Bilstien 5100 struts with the adjustable spring perch (3 settings) or a spacer that sits on top of the spring. Most use the spacer and it is easy to remove but you will need to take the struts out of the truck. Most garages should be able to do both sides in an hour. You will need an alignment as well.
If they used the Bilstiens, you can keep them and lower the ride height back to stock by adjusting the lower spring mount. Involves removing the strut as well to do this.
The other option is to leave it as it is. Assuming the hitch is set up correctly, 1" of sag from unloaded height is reasonable. It just looks like more because the nose started out high. As long as your headlights aren't bothering other drivers it should be fine.
Bags can take the sag out but can have a negative affect on the WD hitch which can make it difficult to set up correctly. They do help smooth out the ride though and will lift the rear. Airlift and Firestone make some good ones for around $350 without the compressor.
