You didn't state where you're coming from but to get to Paradise (doable with your 45'), only come in from the south on 123 from Eckerman. However, I'm not sure where you would stay up there with your 45'. Definitely try to stay somewhere else other than Paradise and just drive you towed vehicle to the Paradise area and visit the Great Lakes Shipwreck Museum at Whitefish Point just beyond Paradise. Tahquamenon Falls is at Paradise, too. Both are worth a visit and you'll get great views of Lake Superior.
To get to Muskallonge Lake St. Pk. only come in from the south from Newberry 123 to CR407.
Don't try to go from Muskallonge west to Grand Marais along the lake, that's gravel.
You don't want to use any gravel roads - too narrow.
If you want to visit Pictured Rocks Nat'l Lakeshore, 28 to Munising is where you want to end up. Personally, if you want to see the lake, skip Muskallonge and head to Munising.
If you're traveling across the Upper Peninsula, the Houghton area is great. Have a good trip.
Full-Timed for 16 Years
.... Back in S&B Again
Traveled 8 yr in a 40' 2004 Newmar Dutch Star Motorhome
& 8 yr in a 33' Travel Supreme 5th Wheel