HondaFan - During my last valve clearance check, I had an "ah...haaa" moment which is rare for me!
I always do the valves on the rear cylinder FIRST because it's so easy to access once the airbox is removed. Once those were done, I reinstalled the rear cover then I turned the crank until the mark showed "TF" which means TDC front cylinder and this was when the lightbulb in my pea brain came ON.
With the crank at "TF" both exhaust rockers are UP making rocker cover removal difficult. So I continued to turn the crank about 1/4 turn so the exhausts would open (with rockers DOWN), then I had plenty to room to get the cyl head cover past the frame crossbar. With the cover removed, I turned the crank almost of full rotation to get it back to TF and checked the valves. And of course, once that was done I did the 1/4 turn of the crank to get the ex rockers down so I could reinstall the cyl head cover.
ps. I've never removed the radiator to do a clearance check and have always devised "workarounds" to avoid radiator removal because anti-freeze draining makes such a mess...at least it does for me!