I have repaired quite a few with silicone. I think that is what Scamp uses. I'm sure Proflex or Quad sealant will work.

1. Drain tank.

2. Block up drivers side of trailer so no water leaks onto the joint.

3. Remove old sealant and clean joint. I use alcohol because acetone reacts with the tank and ABS line.

4. Next, the most important step. Make sure line is secured tightly to the bottom of the trailer. Block of wood between the line and trailer bottom. Tighten  plumbing strap so there is no play.

5. After making sure the mating points are completely dry apply a liberal coat of silicone or sealant to the joint. I use a squeeze tube of black silicone usually available from an auto parts store. The tube is easier to deal with and the black silicone is not noticeable.

6.Wait a day to cure and you should be good to go.

This is also a good time to inspect/clean/lube or replace your dump valve.

Eddie