I don’t really recommend CP Baron in jungle unless your team is fully committed to rotating to defending you, like you’re a CP Saw.
He snowballs hard, but he has to get the last hit on everything to make it worth it. It has rewards really early in the game: once you can build a CW and, I prefer BM early because it counteracts any defense items they build and makes each mortar that much deadlier on its own, then he’s fine to roam as long as your positioning is on point, and he can reliably deny for his team early game, but one of your first items has to be an energy battery. You can decide between a crystal or an hourglass as a second but you’ll find you’re running out of mortars too often without hourglass, and you’ll need a void soon after anyway. You really gotta pace yourself at the beginning between mortars and your basic to make CP Baron work, kinda like Varya and stutterstepping with her early to save energy, and I find putting an aftershock on him is one of the only uses for his basic, because once you build up you don’t need an eve: you should be far, far away from immediate action by then, so your B becomes an aftershock proc finisher for anyone who runs, with a little health regen, but you could get a sorrowblade/spellsword instead for the slow or extra cooldown if you want it.
But yeah, unless your teamates are rotating every other second between lane & jungle to help you, or you buy flares and mines, a good koshka, or really any melee in the jungle, is going to harass you out of your gold. Best thing is to get a capt. to harass whatever enemies decide to go for middle treant while you bomb them to chip health, then get help grabbing lower jungle camp treant on your side, go back to lane and help there as a team, then make it back to jungle yourself, with some defensive mines to help give you awareness. With that strategy you can farm pretty well, but you need coordination.