If you can find a frame that has a low standover/short seat tube (410 and 400 on my bikes). This is important because getting air is much safer with the seat as low as possible and you shouldn’t really be sat down at all when pump tracking! A shorter reach than your usual, somewhere between you and your Mrs will be fine. I’d fit a stem that’s a little bit short for me and little bit long for her, with some nice high rise bars. Slack and long reach aren’t necessary or advantageous on pump tracks!
I use an NS Eccentric Alu Evo with 26 inch wheels (it’s 27.5 frame with a 27.5 fork) for this exact purpose. It’s light enough for less powerful people to throw around, is a really capable trail bike (I’ve had Blue Pigs before) and is reasonable enough on pump tracks.
To be clear a dirt jump bike with short travel/rigid, low profile tread tyres (pumped up solid) is best for (mountain bikers) pump tracking but would be pretty compromised on all but easy flow trails. You can’t have it all!