Lake Havasu is awesome. Plenty to do. You should look at renting a house and boat, as you will have a place to crash, shower, bring ladies... if you find one, and park your cars.
Call the local side by side rental places and see if you can rent some side by sides, there is plenty of great offroading on all sides of town, except maybe the west, but you should be on a boat there.
Sams Shooters Imporium is an indoor range, it's OK. They have some machine guns, but ammo is scarce. I find them to have a bit of an attitude (can't really blame them) but they do have a range. There are other places around to shoot, there is also a range down by Sara Park, just south of town but it's private.
The bars are opening now, and things are mostly returning to normal. There are no strippers in town, no strip clubs, so if that is a thing you will probably have to bring them in from Vegas, or from LA/OC.
I live here most of the time and still unfortunatly work in Ca. I only go back when I have meetings, or have to do somethig that can't be done remotely.