Hi Pomp,
I've been away for awhile....
Have Reaper save every x minutes (15 is default). In reaper preferences go to project settings and at the bottom of the page...set the desired time....then change the pull down to "any time" that way if your mixing (as well as recording) nothing gets lost. Then check to timestamped file in the check box.
After a crash, you can see all the saved files by using the "open project" command and changing the pull down menu in the right bottom corner to show (*RPP-BAK) files. Pick the most recent one and you're back to when your file was automatically saved......
igg