Lol. Yeah. I mean, the fact that it is actually a paid content (which we all know how insane the price is) gives no reason for me to ignore the challenge that's only filled with fairly simple tasks.
Anyway, for Solo Challenge #1: You can find a fairly big base at the south of San Mateo. Just fly a heli and check out a base with 5 cars parked. You can find the other 3 cars on other bases nearby.
Solo Challenge #2: If you're coming from San Mateo, I suggest you to pick a SB helicopter before flying to Tabacal. In the southwestern part, there's an (empty) farm beside a known Rebel hiding spot (not Rally Point) and you will find another single SB helicopter here. Park yours close to it and C4 them. Make your way riding along the river on the west side of Tabacal and you will spot a heli parked on the river bank, but that's already under Media Luna province, so hijack and make your way towards the centre of the map where you can find a big SB base with helipad on the ground right beside a railtrack and tunnel. It's being watched and has jammer. So you do your thing here, but don't die.
Solo Challenge #3: I find this one as a good objective to train your distraction and stealth bombing skills. Breaking the generator with gun won't work. You have to blow it up; destroy it till it burns. I don't know about Villa Verde, but in Espiritu Santo, there are two generators. One is in the base nearby in the south of Espiritu Santo Delta, which is crowded and and packed with vehicles parked close by, it's good to be your practice ground. Another one is in south part of Espiritu Santo Base, which doesn't have people nearby within the explosion radius. Simply approach from the jungle, you will see a watchtower, a jammer, and a few people around there. The generator would be just at your left hand side, beside the cliff. Just creep your way to the cliff, throw a nade, and move out. They won't find you.
Oh you're back! Where did you disappear into? lol