Your Coachman is nearly identical to my TT in the sig below. You should have a quick-connect LPG port at the rear outside kitchen. Look under the bottom of the kitchen to see if its there. A short hose is supplied to connect it to the grill when it is pulled out. If not, you'll have to install one by T'ing into the line where it goes up into the inside kitchen area. Run the line back to under the outside kitchen, elbow it to a shut-off valve and quick-connect fitting. You do not have to install a line prior to the regulators up front, in fact, that is dangerous. Your grill has a regulator on it, it is not a high pressure grill.
Ours came with a 2-burner slide-out grill also. Its OK for doing small stuff like eggs and such, but you'll not be able to cook with the lid down. Best thing is to spend $150 and get something like the small Weber Baby Q, and run it off the LPG line you have or need to extend. Then just get the proper 10' hose, set your Weber on a table near the kitchen, hook and cook. You do not need to remove the regulator from the Weber like it been told on here in other threads, two regulators in an LPG line is no problem. Thats how we do ours, and it works great.