Consider using "Goop" brand flexible epoxy sealant/adhesive. You can find it at Lowes and Home Depot. Comes in a squeeze tube. Sell for $4.00+-. Goes on easily. Dries clear. Flexible and it will not let loose. Does not discolor over time. Once applied you hardly notice it. Goop is really quite the stuff. I've used it to patch plastic sinks, pvc/cast iron sewer pipes and more.
I wrote this a ways back on another forum:
<span class="ev_code_BLUE">Often times when working on an RV, etc. you need to glue something. Unfortunately, silicone, epoxy and stuff just does not hold up. The silicone does not hold and the epoxy is to brittle and breaks, cracks when you hit the road and vibration occurs. Anyway, go to Home Depot or Lowe's and buy a product called "GOOP". It is a flexible epoxy contact adhesive/sealer. You will see various packages of it at the store with various labels such as Marine, Plumbers, Automotive and such. From what I can tell it is all the same stuff with a package color change BUT I can tell you this stuff is fantastic. Unlike regular epoxy adhesive which does not hold up well to vibration and stuff, this "GOOP" is a tad flexible and it holds up under extreme vibration conditions, etc.. For more info on this product read HERE. By the way, IF you ever need to get the epoxy adhesive to let loose, use a heat gun or hair dryer on the Goop for a few minutes as the heat will make the GOOP let go. For the record, I have used this GOOP a few times when making custom, LED Harley brake lights. The stuff is great and even an old Harley vibrating as they do can not break loose the GOOP used in assembling the brake light. Cost is $4.00 or so for a decent size tube. I usually buy the Marine GOOP but again seems they are all the same and labeled as automotive, marine and such just as a marketing ploy. Regardless, terrific stuff that every handyman should have on his bench. Hmmmm, I even used it to repair pinhole size leaks in a cast iron sewage pipe...</span>
Eternabond is terrific but geez, would look like crap on a sink, tub, etc.