Here:
http://opl.psx-scene.com/Covers.html
"ISO Support fuer USB und LAN" is already commited btw (or maybe I didn't understand your sentence well)
For ISO support, follow the naming convention rules, read here or make some search:
[release] Open PS2Loader V. 0.7
For "white screen", it is usually due to fragmentation, or bad rip (in general), bad naming of file (for ISO), ...
Finally it is your job to post "reports" not mine Btw it is not very constructive to say "it works in USB advance", only interesting point is your problem with Monster Hunter, as it looks like a regression.
I warn you atmosphere on psx-scene is tense there ... so be sure to report in the corerct way. Give useful information, your ps2 model, the device mode your are using (USB/ETH/HDD), the exact name of the game with game_code (SCES,....), which version of OPL run the game and which revision doesn't work anymore. With such information you are sure your bug/regression will be corrected. On the other hand, you might experience unpleasant reaction.