Stayed there for several nights the end of May about 10 years ago. At that time, the sites were fairly small and tight, lots of trees. Didn't go into the showers or laundry, so am not sure what they were like We had a 36ft DP and did fit ok, we had to be in the area for a wedding and didn't have a lot of choices.
If at all possible, I would try for either Burlington Bay and the city park in Grand Marais. No restaurants, shopping etc near Lambs. Both of the other parks are within walking distance of shopping, etc. You need to make reservations for both parks as soon as possible, they are popular and are full most of the time.
Unless Lamb's has upgraded quite a bit, I would pass on them and stop in Two Harbors or continue on the Grand Marais.
Safe travels