I rarely sit bolt-upright (no pull back bars, just Nitto Wavies), but most of my bikes have the bars are considerably higher than the seat so I am fairly upright. I am a couple weeks shy of 66, but I just feel too tippy bolt upright, I have been riding mostly drops for 50 years. When riding the levees recently on my single speed Mystery Bike, 1st I chose the direction of the ride carefully - start into the wind, there is a handy weather station at the getting on the levee start point and I look at which way the wind vane is pointing. Last weekend the winds were in the 10-20 mph range and the single gear is 60. I have a Da Brim on my helmet and the wind can definitely move my head around when it is gusty. I just ride into the wind with elbows bent, slide back on the seat, for as long as I can (a little more than an hour for now) at slightly over 6 mph then turn around and get an assist on the return.
15-20 years ago, I used to get sent down to Ascension Island (South Atlantic - about halfway between South America and Africa) as a civilian contractor and I took my Bike Friday (1x7 gearing) with me. The wind there was 20 mph or more from the east, fortunately the base on on the west side of the island, so I could ride out into the wind. I had to pedal down the hills. It was about three hours out to the old NASA site and 1/2 hour getting back, barely had to pedal uphill. Bars were a little above the seat.
I am now working on my Mean Green Levee Riding Machine - putting gears on my formerly single speed Rosco Bubbe V1. It will remain upright, with the shifters on the downtube to discourage shifting unless needed (2x9 - 48/34 with 12-29) with Rene Herse 700 x 44 tires. Should be easier into the wind.
Just for grins - here is my Guv'nor with three speed shifter mounted on the seatpost - pretty much impossible to shift while on the bike - stop and dismount to shift
Laing