Hotel-wise it looks like the closest set of hotels is about 2.5 miles away. The Hyatt House Portland/Downtown is 12k/night, your UR should transfer instantly to Hyatt. Hotel would be refundable until 24 hours before I believe.

Using the Chase portal to book flights directly is a good thought but if you do have to cancel it will be the same as a normal revenue ticket which means standard airline change fees and prices are high (best I can find is about $800/person which translates to 54k/person if you have a Chase Sapphire Reserve or 64k/person if you have a regular Chase Sapphire card).

This is the absolute best thing I can find that comes closest to hitting your needs: https://flights.app.goo.gl/yuNNn -- it sends you via ATL on the outbound (avoiding potential weather issues in DTW/MSP) but requires going MSP on the way back, the 2pm DL flight on PDX - MSP seems to be the only afternoon flight across the board that hits a major hub with enough time to connect onwards to the east coast on Sunday (though you'd get in a few minutes after midnight