To the OP BurpMan,
Having a spending limit of $30,000 is going to be a challenge to find a 4x4 motor home in very good condition. I advise to search weekly Craigslist nationwide, RV Trader, RVT, Camping World, and rvUSA. Just maybe you will get lucky and find one in decent condition, in your price range.
I also advise to be careful when shopping for a 4x4 motor home. If the previous owner or owners explored hard with it, you might be buying a hidden twisted frame or a twisted house with breached seam work. Don't buy one in the blind. Inspect it very carefully. If things like doors and seams don't align right, then don't buy it at any price.
Just about every motor home is built to be driven on reasonable surfaces. Traversing rocks and such can twist the house rendering it a bad purchase. Earth Roamer and a select few others are built for traversing rocks, not the majority of motor homes. A typical motor home with a 4x4 conversion is meant for much lesser challenging trails and sandy beaches as your planned use.
Phoenix Cruiser 4x4s are better constructed than your average motor home. They will hold up better to 4x4 trails, but they too will have limitations with regards to rock traversing. If you find a PC 4x4 cream puff, you might want to look twice at it and consider increasing your spending budget. PC 4x4s come in 21 to 31 foot lengths so there is potentially a wide range of flavors in the used 4x4 market. But PC 4x4s in general are uncommon. All of them will have the Quigley conversion.
One thing that bothers me about any 4x4 conversion is the high stance. The ground clearance is great for 4x4-ing, but what about all other driving? Highway driving is less than ideal in a normal motor home. What is it with the rig raised up so much higher?