You can but definitely watch a YouTube video on the procedure you don't want to pump RV antifreeze in without the motor running. You may want to get a shop manual for your boat, Sea-Doo has an excellent step by step procedure in their manuals. Keep in mind Sea Doo recommends blowing the water out vs using rv antifreeze.
This isn't to get into a debate of RV antifreeze versus blowing water out with compressed air but my imagine there is a reason Sea Doo does it the way they do it in their manuals. But at some point it's a matter of personal preference.