Sounds like things are going along just fine. First, if the estimate is only $1000 on the truck, there is basically nothing wrong with it. The shop has a vested interest in finding as much wrong as possible. They are more beholden to their bottom line than they are to any insurance company. $1000 parts and labor doesn't go much further than replacing a license plate bracket. I broke a power side mirror on my truck a few years back and that was a $650.00 repair. Your truck will be fine and any reputable shop is going to warranty their repairs for a period of time.
What is the damage to the trailer? If you were actually going 60 MPH and were hit by someone going 85 there really shouldn't be much left that is recognizable as a trailer. If there is significant body damage the repairs are going to exceed the value of the trailer very quickly.
You don't want the trailer repaired if there is major damage. Argue that not only is there the very real possibility of hidden damage, you are suffering loss of usage every day. Push for having it declared a total loss. Since you have gap insurance (a good thing) you are going to actually come out ahead if it is totaled. You really won't be concerned about the value they give you since you will actually be collecting the total amount of the loan value (loan will be completely paid off by the gap insurance and you don't care if the gap is $2000 or $10000). Since you appear to have been upside down on the loan before the accident, you actually are making money if they total the trailer (you lost a $17000 trailer and are getting a $22000 loan paid off, that is a good transaction financially). Contact the gap insurance carrier and they will walk you thru the process once the insurance company has agreed to declare the trailer a total loss. Once the loan is paid in full you can go shopping for whatever you want to replace it.