EDITED
Set the rangefinders up correctly, downward facing and so on with RNGFNDx_ORIENT
then setting RCx_OPTION,10 enable or disable Rangefinder (I assume all rangefinders) and a corresponding switch and channel on your transmitter.
It’s almost impossible to buy a frame that doesnt need modifications. You will just have to do your best with trying to tighten up the arm folding mechanisms. Pay close attention to all the wiring too - it must be secured to the frame (not floating loose) and have just enough length and flexibility where it plugs into the flight controller so it doesnt transfer vibrations. The wiring should not be bunched up and pulling tight on the flight controller either.
Do some searches - there is some good discussions somewhere here with before and after shots.
Start with this one:
I also meant to say, for takeoffs and landing it’s good to have a large heavy mat of some sort, to keep dust and debris away. Heavy so it wont blow around, and it needs to be porous or fabric on top - not a smooth impregnable surface. If you cant get any of that “composite” rubber mat used in play grounds as soft-fall, you could try attaching a some old heavy duty rug to a sheet of rubber, or just use the rug. if it’s heavy enough.
https://www.bunnings.com.au/swing-slide-climb-1-x-1m-x-20mm-shock-pad-rubber-paver_p3321609