My (rather old fashioned) take and advice - put a good frame pump on your bike. Now you can alter pressure at will while on the roads you ride. Each time, pinch the tire to get a feel for it. Develop that pinch sense in correlation to the ride feel and strike likelihood. (I've never run tires so soft. A pinch might not be the best approach. Perhaps a full squeeze with you hand? Push the tire down into the rim? Whatever.
With your "pinch" well educated, you will no longer need a gauge or pump/cannister with gauge and with just that one pump will be able to ride anywhere with confidence. (My garage pumps have gauges. I squeeze after pumping to keep my hand's education current. Yes, road pressures, 85 to 110 psi; my hand would flunk your test like a doctor would the LSAT exam for lawyers.)
I do not know what the best frame pump is for big tires, low pressure. I use the excellent (for road bikes) Zephal HPX pumps. I'd research to find a large diameter pump with the same high regard as the HPX.
My gravel experience is limited and I have stopped doing it as it is clear that often rough gravel is harder on my NFL-syndrome brain (bike crash TBI) than I have any business subjecting it to. But while I dallied in it I rode about 35 miles of Oregon coast range logging roads on 1-1/2" gravel and several thousand feet of up and down plus another 60 miles of pavement on a crazy 90 mile day.. 38c front and 35c rear. The HPX. I had the proper pressure all day, adjusting several times on the gravel and riding the pavement at close to 70 psi. No flats. But my pump got borrowed maybe a dozen times to bail out others. (A dozen of us. I think two went flat free.)