I successfully used a Porter Cable pancake compressor for both jobs, but for blowing out lines, it barely did the job even on my old pop-up. I don't think it could handle the task on my newer, larger rig. It's great for tires, but a small pump and tiny pressure tank means that you must disconnect to allow it to fill, then blast the contents of the tank, disconnect, fill, blast, over and over (or connect with a 1/4 turn ball valve to shut off air flow as it fills).
The answer is to have two compressors. I have a ViAir 90P for tires. This connects straight to battery terminals and can draw about 23 amps, so it can really pump some air. (Cigarette lighter It has a decent duty cycle - 15%. And it runs on 12 volts. You can run it off your RV battery bank or your TV battery...keep the TV running. You can use jumper cables as an extension cord.
If, like one commenter, I was going to air down for off-road use then air up, I'd get a much better ViAir with a far longer duty cycle. This would be the gold standard: https://www.amazon.com/VIAIR-20020-S...s%2C231&sr=8-6
NOTE that duty cycle is a big deal whether you're using a 120 volt portable or a 12 volt tire inflator. It's one thing to air up one tire due to a leak. It's quite another to air up 4 RV tires and 4 to 6 TV tires after a jaunt in the dunes. That pancake won't hold up long under that kind of abuse either.
At home, I have a large portable compressor rated for 175 PSI and with a 30 gallon tank. This compressor is up to the task of blowing lines dry. Just set the output pressure to about 40 PSI and, let 'er rip. You can work continuously, from faucet to faucet to drain until everything is bone dry. This is not a pro compressor, but it's very well suited for serious home projects and RV maintenance. https://www.homedepot.com/p/Husky-30...303H/206532808
My Husky sits in the garage/shed like a stationary compressor. I have 300' of hose (from Harbor Freight) to make it possible to reach almost any spot on my property without moving the compressor.
This is rated to deliver 6.8 SCFM at 40 PSI. A pancake will deliver half of that...and that's wishful thinking.
In the case of compressors, one size does not fit all. Any small, portable unit simply isn't up to the task of air winterizing. A 120 volt compressor requires a big inverter or a generator to power it in the field. A pancake is large and a lot to store in the RV or TV while being anemic at best.
A good 12 volt tire inflator will serve you well in the field, and a good "real" compressor will serve you well at home...especially when it comes to inflating tires to 80 PSI or so. A pancake may claim a max pressure of 135 to 150 PSI, but you'll often find yourself struggling to inflate a tire to 80 PSI, because the low pressure trigger on the pump often won't kick the pump on unless you force the issue by bleeding off air and then waiting for the tank to pressurize. With either of mine, if you want 80 PSI, you get 80 PSI with no shenanigans necessary. The Husky makes serious pressure, and the ViAir pumps continuously.
There are vastly superior versions of both types of compressor. These were the sweet spot for my needs.