Can L18 and L47 coexistn and what about plants?

My LFS has a couple of L18 gold nuggets and a couple of L47 Mango/Magnum plecos for sale and I was thinking about getting one of each. They are around 2" in size and would be going into a 75 gallon tank for the next year or two. I know these plecos get pretty big and intend on moving them to a 240 or 300 in a couple of years, but would they get along at this age in a 75, and will they get along later on down the road in a 240 or 300?

Also, will either of them destroy my plants? All of my tanks have plants in them, and the last thing I need is a pleco that munches on plants.

Thanks for the reply. Since I have 6 compact swords in the tank, I guess they are not going to be on my list of fish to put in the tank. That sucks. Looks like I'll be looking for an L81 for the tank instead.