Obviously a tag axle is there to carry extra weight. I don't know of many coaches that offer it as an option. The weight dictates a tag axle.
The pluses are that it helps prevent porpoising and forces the coach to drive straighter. If you are going over a speed bump, the drive axle pops up and is softened on the down side by the tag axle.
In the event that you are noticing wear on the front tires, you can switch the tag tires to the front. We did that with our Dynasty when we got a bad alignment at Colton Truck in Colton, CA. I didn't catch the beginnings of extreme wear until Nashville. We got a perfect alignment at TAFA (Truck Axle Frame and Alignment) in Nashville.
A diesel fired furnace system just can't be beat. First, it's pulling fuel from the huge on board fuel tank so there are generally no worries on running out of fuel as long as you start full.
Our previous coach had Aqua-Hot and our current coach has a Webasto system (similar to AH) with a 20 gallon water tank (electric/diesel) along with a tankless system for the shower.
MM.
Mr.Mark
2021.5 Pleasure Way Plateau FL Class-B on the Sprinter Chassis
2018 Mini Cooper Hardtop Coupe, 2 dr., 6-speed manual
(SOLD) 2015 Prevost Liberty Coach, 45 ft, 500 hp Volvo
(SOLD) 2008 Monaco Dynasty, 42 ft, 425 hp Cummins