Hot water bypass
Yes, blow out the lines with the bypass in its normal configuration, and then put it in its bypass configuration. That removes the water between the valves and the tank. I typically blow out lines one valve at a time. So once the water heater is done, I start at the kitchen sink. Turn on the air pressure and blow out the cold, then the hot, and then the rinse hose. Then I go to the shower and do the same, next the bathroom sink, then the toilet and rinse hose, outside to the outside water valve, and finally to the hot and cold low water valves.
Keeping the hot water bypass closed, I reverse the process adding RV Antifreeze in the same process one valve at a time in the same order.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700