Our gross neighbor left bugs behind, now we have them. HELP!

Our neighbor was a disgusting pig and has finally moved leaving roaches behind. There's no other spot to move to and other rv parks around us are full. I am assuming this rv park doesn't spray for pests. There are spiders, crickets, and flying insects everywhere. These roaches are now in our rv and I am doing everything I know to do to kill them and keep them out. They only seem to like to hang out around the sink. I make sure that trash is tied, that all food is either discarded or put away, and that's still not doing the trick. I see them in the sink sometimes and I wonder if they're coming up through the grey tank somehow. Anyway it's driving me insane. Not to mention that it really, really grosses me out to be around bugs. I would even say it's a borderline phobia. Anyone have any tips or products we can use. We did buy this thing that you spray the grass and it's supposed to get rid of bugs. So we may have that part covered, I just need to know how to get them out of the camper. Oh, we have also used that combat gel, which isn't really doing any good because they don't seem to be going in the places where it's laid. Maybe they are, and it's not working I don't know. But whatever is going on, wherever they are coming from, they're still getting in. Thanks for any help or advice. We are not gross people, I am a neat freak, but this is making me feel dirty and disgusting.