OK, so to summarize what I've read from the original post. Buyer DOES want to motor it. TITLE and REGISTRATION IS REQUIRED in MO. There are many ways of accomplishing this. Yours seems to be the correct way to get a title. I don't believe that the ladies were being female dogs in this instance. (many times they are guilty). Now looking at the whole scenario, you have owned the watercraft for (X) number of years, the State wants tax dollars. You are not required to title it if you are going to paddle it, but if you motor it, your required. ( I know I'm beating a dead horse here). Now, you want a title on property that has been owned for (x) number of years, but has not been taxed because it was not required to be. I would ask the lady at the license bureau if I could title beginning today due to the law stating that I don't have to title if I am not using a motor, and have not used one. This may be the way to save you the late charge of $30.00, and also make it to where you do not owe for back taxes. You would still have to pay for title fees etc.
just my 2 cents. I recently registered a 10' jon boat because I would like to put a trolling motor on it. I had to file for an abandoned property title, go through highway patrol and all. It was a mess, but I was able to get through it. Took about 6 months.