Thanks for everyone's ideas and creative thinking. Talked with a "dealer/jobber" today and just like Gary mentioned, a minimum of 200 gallons and a surcharge is what I'm dealing with, with a tank. Talking with dealer and listening to advice above (cowski), seems like danger of dirt, algae, water, etc. might come into play if I got a big tank with my usage level. Looks like I need to go with 60-70 gallon unit for truck/trailer. Probably go with a unit similar to what 94BULLITT pointed out and mount on skid and remove with forks when empty or only slightly full. Northern Tool has a 25, 55, 75 or 100 gal unit that has pump, hose, electrical lead with battery clips...as self contained unit. A little pricey but I'm thinking it might be worth it. When I come up with my exact solution, I'll let everyone know.
Thanks again for ALL the very helpful comments.