I run a mod v 15' DuraCraft hull (with pods) and a long tail. It has the short transom (15"). I currently run a 23 hp. Backwater Long Tail. It is the 59" model. We generally run in cattail marshes with 3" to a foot of water, and occasionally submerged logs and branches, and lots of vegetation. This set up is OK and works well for us. It is not the fastest boat out there, but we aren't racing it either. Our normal hunting load is 2 guys and 2-3 sacks of deeks, 1 battery, 3-5 gallons of gas, guns, ammo, dog, blind etc. Like I said, it does the job. Keep in mind that a long tail is a simple as it gets, and dependable. Right now with that load we are doing about 12 mph, but I believe we have a wrong sized prop on it. I have been told (by Backwater) that with the right prop we should expect 15-18 mph.
The point of all of this is that yes, you can run a LT on a mod v boat. One point, if you have the tall transom (20") be sure to get the Long Long tail (72"). Anything less will result in a loss of performance, due to the less than optimal point of entry of the prop into the water. Also, go over to mudmotortalk.com for more info than you will ever need.
Lastly, find another dealer. That is too much for a used LT, and way too much for the short tail.
Hope this helps.