320 is unlikely even in summer tbh, but if you managed it it would likely be nervewracking. 260 should be just about manageable in winter but again might be scraping the bottom of battery. trick will be to use zapmap to find a few fast chargers enroute at about 120/160 miles out. hopefully a 30 min charge will be enough. go for a coffee and comeback and on your way.
Current Car: Hyundai Kona Premium EV...2 way 40kg hoist
Last Car: Toyota C-HR Excel Hybrid...4 way 80kg hoist