Some of the over 55 communities have rental restrictions, but not all do. The one 55+ community in Marlton has only 1 rental available that I could find, at $2500 per month. Its a single family home 4 bedrooms 3 baths.
Mount Laurel has a few more in Holiday Village. There may be some homes on the market for sale that would consider a rental if they are not getting any offers to purchase.
If you need more assistance, get in touch via email or cell phone. I've lived and worked in Mt. Laurel for about 18 years, and I'm very familiar with Marlton also.
Best of Luck,