Steam – Just Cause 2 on Steam hanging on “Preparing to Launch”

I've never tried online play myself.

The brilliant guide RTSC Startopia has a few notes on its starting page. In particular, they say:

• That online play, different from LAN play, doesn't work well. (Yeah, you figured that out yourself.) Meaning it's probably caused by desyncs due to the higher latency, something many older games struggle with.
• That the autosave helped them after the frequent crashes.
• That there's a rumour that the autosave itself causes the crashes and that disabling the autosaving by write-protecting the file might help. (Could this explain why it's almost after ten minutes for you?)
• Do not try to save. Do not pause. Do not open the menu. (More indicating that desyncing is the issue at hand.)
• That you shouldn't get frustrated by crashing multiplayer games, because it will just happen a lot. (Probably the most helpful tip, but also much easier said than done. :))

Try removing the only mod (the "glowing ore veins mod") you have, just to check if does not really cause the crashes.

Also, it might be the case of the ol' Savegame bloating. Try the Unofficial Skyrim Patch (UKSP). Among its fixes are:

• NPCs will no longer drop weapons or shields as separate objects, as these are never cleaned up which greatly adds to save bloating and litters the gameworld (the items will still appear to be dropped, but will access the corpse's inventory to be taken and be cleaned up with the corpse if left)
• Ash Piles, Ghostly Remains, Ice Piles and Wisp Cores will no longer permanently remain and bloat the save file (they will either disappear on exit of the cell or when the cell resets)
• The torches on sconce activators will no longer duplicate-in-place (also adding slightly to bloat) when their cells respawn; the duplicate(s) would remain when the player picked up the newest torch (note that this fix is not retroactive for existing duplicate torches; simply open the console, click any duplicate torch and enter delete to get rid of it and no new ones will appear)

The Unofficial Skyrim Patch is a comprehensive Skyrim bugfixing mod that could also help solve other potential CTD issues. Full list of its fixes here.

The mod, Possessive Corpses, has a 'less arrows' module, which has this feature:

The amount of arrows per cell (not counting the ones in inventories, droped or attached to actors has been reduced from 15 to 5.

From the mod's description:

Missed arrows aren't deleted by the game, but there is a max number of arrows allowed in the world. Once you (or another actor) fires an arrow pass that limit, the first one being generated is removed. This way, arrows can last months but won't ever pass the limit number. In my game that number is 15, but Those of you with ultra settings may have a greater number (I really don't know what controls this number and if can be changed at all).

I'd use only the 'less arrows' module of Possessive Corpses with UKSP (as the other features of Possessive Corpses might overlap with UKSP).