debug CGI with complex forms

[Sullivan WxPyQtKinter]

When the form in one HTML is very complex with a lot of fields(input,
button,radio,checkbox etc.), setting the environment is quite
burdernsome, so I usually change the stdout and stderr of the submit
processing script to a file object to see the output directly from that
file. This just can do, but still inconvinient.
Anyone has more suggestions?