Dolpin and Krusader(if its been ported fully) are the only QT4 filemanagers I know. But you do have other choices
Code:
% ls /usr/ports/x11-fm/
FSViewer gnome-commander rox-session
Makefile gnome-commander2 tdfsb
asfiles gprename thunar
catseye-fm jaffm tkdesk
cfm krusader twander
dfm krusader2 velocity
dolphin mtoolsfm worker
emelfm2 mucommander workplace
entropyfm nautilus x-files
etoile-fontmanager p5-PerlFM xcruise
ezfm pbi-thumbnailer xdiskusage
filerunner pcmanfm xfe
fsv py-nautilus xfm
gentoo rox-filer xnc
gir-repository-nautilus rox-mime-editor xplore
I would not advise installing anything that can not be found in ports but there may be something out there that does meet the criteria you have set.