As for rtwp, I've used web and pit spells in this fight. No idea why you think it is not feasible. It doesn't really matter if some of the allied units run into them, they don't care.
The problem is not your allies to go into your pits, webs, stinking cloud, grease, etc, is your hasted party members happily running into them in RTWP, even if you have ranged weapons. Maybe I phrased it wrong, it is possible to do it in RTWP indeed, I just do not enjoy playing in that mode much, I only use it to finish quickly trash mobs.
