When we were there; in 2010; we stayed at the " Elkhart Campground " wide open spaces, north side of town if memory serves, not sure about pet policy. RV dealer next door, and about 1/2 mile from both surplus stores, that you were asking about.
Hope you find what your after , and if you have time , try to fit in a tour of the Newmar factory.
I hadn't bought my coach when I was there , and missed the 1 PM tour ( last of the day ) spent too much time enjoying lunch at Amish Acers ? right next door in Nappanee.
Can't find any contact info for the RV park , in our travel log , maybe Google would be a help.