most suspension part are rated to 300#, even the upper end air forks. I'm digging pus size tires, 2.8-3" range. You can run lower pressure and feels like a bit of air suspension or a floating cloud on deeper sand. Your old MTB likely had coil and oil fork.
If you find the suspension forks not working, you can swap them out for steel rigid for $150 or less, drop weight and install the suspension fork later. Keep in mind the Axle to Crown dimension when selecting forks as it will mess with bike frame geometries head/seat angles.
29plus tires
https://surlybikes.com/bikes/krampus/bike_specs
There should be TONS of shops in portland that can help/test ride/fit bikes for you.
I have this one in R+ build in 275plus tires, but there is a cheaper D+ one that might work for you. The SRAM fork says 120+psi for 200# rider, with max PSI of 205psi
https://www.santacruzbicycles.com/en-US/chameleon
fork manual
https://sram-cdn-pull-zone-gsdesign....lish_rev_d.pdf
You will have some problems with the wheels at some point, not sure if more spoke options are out there with boosted hubs, never dug around to see,