From what i gathered. long term is NO. Short term is yes.
No you cant stop the bottom from rusting. The way they are made- the welds allow for some moment that ultimately cracks the undercoating and lets moisture in. I guarantee you that there is some rust under that undercoating. Look over it with a fine tooth comb and find ANY cracks or tiny seams that are starting and seal them up. aka take off the undercoating in that spot and re coat with some epoxy paint and then re coat. should buy some time. Any tiny scratches or cracks will develop into rust. Every 6 months i do an inspection on my car head to toe while its up for tire rotation and oil changes and i look at all the undersides and such. its a battle to keep it sealed up and for spots to not get worse. I'm just repairing a band aid until its time for a strip/weld/paint job.