I used a roll on/spray on liner called Monstaliner. It is an activated urethane coating, and if you have it sprayed can have the same or less texture than the Line-X. It stands up about the same and is hard as nails. After some extensive grinding and sanding I primed the inside of my tub with mat POR15, and then coated it with Monstaliner. It turned out amazing and so I did the fenders and the front of the tub. The rest of the tub I did with marine enamel. I painted over the front that I coated with the liner, and not only did it smooth it out, but it looks fantastic. So good in fact I wish I had done the entire exterior of the tub with it!
Fenders rolled with a 4" foam smooth roller (very light texture)
Tub with supplied texture roller
Front of the tub, again rolled with the texture roller
Not trying to hog up your build thread (I can delete these if you wish), just showing some options. With a spray gun and 2 gallons of Monsta, you could save a lot and get very good results.
