I hope this message finds you guys well, present circumstances excluded. I am a licensed attorney with over a decade of legal experience handling matters of a similar nature. It is a pleasure to assist you today.
As a housekeeping matter, your company attorney is ethically barred from filing suit in this situation. He is correct here and you will need to hire another attorney (preferably local to you) to bring the suit.
What we have here is a classic case of breach of contract. You have a contract for the loan, which makes you the pri***** *****en holder on the property. As a result, you can sue them and at the very least, you can seize the 5th wheel and liquidate to get some money back. You can then write off the remaining amount on your personal income taxes.
That said, you are going to have to sue them and you need to sue them before long as the statute of limitations has begun to run against you. You have six years to sue from the date of the breach of contract in Utah for a written contract. This is arguably the first time he did not pay...which means that you are looking at March of 2019 (payment would have been due for first time in March 2013 as I understand it).
If you do not sue by that date for breach of contract, you arguably will not be able to do so as you will be barred by the applicable statute of limitations. I say you need to sue soon also because you need to be able to liquidate the asset before it loses all value. The sooner the better from that standpoint.
You can put them on legal notice with a certified letter and return receipt that if they do not begin payments immediately until you are paid in full, you will have to file suit.
If they do not, for any reason, you really only have one other option, which is to file suit.
I know that is tough and puts you guys in a tough spot, but legally, that is all that there is to it.
Let me know if you have any other questions.
Please also rate my answer positively (three or more stars), so I can receive credit for my advice.