I had a Newmar Mountain Aire on a Workhorse W-22 chassis & the 8.1 engine. It performed pretty well, but a 38' coach isn't a performance vehicle! Plus, I've always been a "GM" guy, & had a couple pick-ups with the 454 engine, and enjoyed them. But , I digress.
I currently have a 2020 Newmar Canyon Star (also 38') with the Ford V-10 in it. This coach is about 2,000# heavier than the other one. So not an exact comparison.
But, in my opinion, the 8.1 had better mid-range acceleration than the V-10. The V-10 had better initial acceleration. However, after installing the Ultra RV "Ford Ultratune" in my 2020; it now outperforms the 8.1 in all areas.
A long answer to your question.......BUT......my opinion,either engine will tow your HHR adequately!
Good Luck!