We had a pop up for 20 years. We used an electric heater to keep the chill off, and the furnace was set to come if the heater couldn't keep up. Also to warm things up fast when we got up in the morning.
As mentioned above, the fans are pretty noisy, though.
Can't speak to use for boon docking; we never did that.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10