I understand that general RP text can become long (been there, done that), especially when writing out a variety of stuff relating to the character (emotions, actions, descriptions, reactions, speaking and how they're speaking, etcetcetc) but you might want to end up looking into writing out a certain amount of text, then putting some kind of sign to show more is coming (unless you're RPing with someone intuitive enough to recognize an unfinished sentence when they see one and don't jump the gun before you finish). It does break up the paragraphs a lot, but it's better than nothing :/
I haven't RP'd other than to joke around, in FF, but I have in other text chat mediums over the years (AIM, MSN, Hangouts, etc), and having similar limitations on larger paragraphs (esp if I'm RPing several characters in motion, at once >_>). But the people I've RP'd with can spot when I've left off in the middle of a sentence and can tell I intend to complete that paragraph. So... in other words, hitting enter slightly early. Might look a little messy, though. But it didn't matter as much with the format my friends and I used, since we used *'s to encase actions/feelings, rather than using something like /em.
So, in other words, for example using that idea...
/em wracked his brain for an idea - any idea at all - for a suitable, if not temporary, solution to the problem at hand... but unfortunately, only ------
/em -- one idea came to mind... no matter how unfavorable it will most likely be received. "Hurr durr, lets put a bunch of agreed-upon symbols, like '-----', at the end of the sentence/paragraph of each section of submitted text to denote more text coming, hurrrr :3", he finally babbled. Unfortunately, many a popoto was hurled in Saseal's direction, that day.
/em sheepishly collects the popotos for popoto stew, and attempts to escape unnoticed by seething RPers...