For most VFR flights of significant length I plan carefully, especially
since I like to fly very low.

This is an interesting statement that begs for an explanation. Why do you
like to fly "very low"?

If you fly antiques the likes of Cubs and Champs, there is no need to
fly high. 300 to 500 AGL will get you anywhere you want to go.
With a max cruise speed of 75-80 MILES per hour, obstruction avoidance
takes a long time. Something a mile ahead of you will give you 40-50
seconds to maneuver around.
You can pull back the power and yell at people on the ground.
Any patch of ground without trees or wires is a potential landing area.
Long drivways, country lanes and fields, big yards, beaches, etc.
Not only can you land, you can takeoff.
I have flown Columbus OH to Oshkosh WI and never gone above 500 AGL.
When I flew Columbus to Lakeland FL for Sun N Fun this year, the only
time I climbed above 1000 AGL was to cross a few mountains and swamps.