If it's just for fun as a parade riding vehicle, sure - have fun!
Most Fire Trucks are well maintained, but, they sure have hard lives on the equipment front. Get in from a dead cold start, and race as fast as you can. Usually never getting to temperature. Over, and over, and over again... Yeah, they're supposed to be made for it, but I bet 10K of fire truck life is the same as 50K on a motorhome's engine...
Best of luck on what you decide,
Roo II is our 04 Country Coach Allure 40'
OnDRoad for The JRNY! Enjoy life...