Radalt no good as it will vary as the terrain beneath slopes - the ground is rarely completely flat.
So I think what you are looking for is a pressure setting which reads height above touchdown? You could use QFE then, which does exactly that. I hesitate to say this, as I know it will almost certainly degenerate into a ‘I love QFE vs QFE’s crap’ debate but it’s a thing and amazingly it works!
For the next poster along please note that I haven’t expressed a preference - I’ve used QFE and QNH for circuits with equal skill (or lack of).
ps. I can’t be arsed to be picky about definitions of height, altitude etc. I’ll leave that for someone else.