I’m considering re-purchasing the first (amateur) radio I ever owned (with transmit capability) just for such events. A Yaesu FT-203 handheld.
There is one available, for a reasonable price but my only trepidation is that I still have the scars from the thumbwheel style of frequency changing. Those cogged wheels were very nasty.
The Mk1 290 I have is 3kc off frequency, probably not a big issue on FM but a bit of faff on SSB and my only other option is the FT-736 and 70cm doesn’t transmit anymore. This is in addition to the fact that requiring a low loader to get the thing to a summit would render the activation invalid.