Ford E350 V10 shifting

My 2008 Tioga with a V-10, is an e450, without towing, does the same thing. When going up any kind of steep climb, it goes down to 25 to 30 miles per hour. I know they say that the engine can take higher rpms, above 4,000, and I be alone on this... but I think that is excessive. Yes, some here say the v-10 was made for that, and more, and that lugging is just as bad, but I for one, do not want my engine screaming at those higher revs and going thru a gallon of gas every few feet. That's just me, I just don't want my engine revving that high. During a recent trip this past June, I kept the rpms at no higher than 2,500, in any type of terrain. I may be babying my motorhome, but it is my baby!