When opening a readonly file, it's a hassle. Would be nice to have a single command to acknowledge it's readonly and edit it anyways, like a shortcut to do the tee % trick.
A decent starting point is
cmap w!! w !sudo tee > /dev/null %
for edit:
cnoremap w!! execute 'silent! write !sudo tee % >/dev/null' <bar> edit!
for write and quit:
cnoremap w!q execute 'silent! write !sudo tee % >/dev/null' <bar> :q