This may be a little late....we have the same TT. What I did was drained low point drains, blew out the lines, put plugs back on drain lines and took out the anode from water heater, pulled panel off water bypass (under sink there is a panel, two screws square drive, remove panel and bypass is hidden there) poured the antifreeze into the fresh tank, (4 gallons). turned on water pump, opened valves on the kitchen sink, cold then hot, one at a time. Turned them off Then did the bathsink, toilet, shower, then outside shower until dark pink color was flowing. Opened freshwater drain and drained leftover antifreeze back into bottle and put drain cap back on. Not hard to do just time consuming.
Any other question about you 274, send me a pm. I've been over our TT with a fine tooth comb and know every inch of it.
TT-2015 Cherokee 274dbh TV-2010 Jeep Commander Limited