Hi Nigel, I know you like myself play both guitar and keys in a full band scenario.
I don't know what gear you prefer to use onstage but thought I'd share a recent discovery.
If you are ok with solid state modeling guitar amps vs tube amps you might want to check out the new line 6 spider V series. In particular their stereo 2 12 240 watt amp.
The full range speaker system with tweeters sounds awesome to me running my PSR S970 into its aux input.
So.... an all in one guitar and keyboard amp. And also excellent for acoustic guitar.

I was very lucky to find a virtually brand new spider V 240 with the FBV3 controller on Craigslist for an unbelievable price I couldn't pass up.
Retail cost of $500 + $250 (amp with pedal)
My cost total of $350
https://youtu.be/5Bf8LS6uNl0