I recently moved from North Carolina to Michigan...
I drained my tanks... put the sand, decor, fish and water in Rubbermaid tubs... Loaded everything into a Penske and was on my way...
When I arrived in Michigan I set up the tanks, added sand, decor and filtration...
Acclimated fish via drip method... then added fish...
Monitored ammonia/nitrite for a few days and water changed as needed to ensure bacteria was established...
You could set up the 55 gal at one location, transfer the fish into it, move the 75 gal, then go back for the 55 gal... But in my opinion your just making more work for yourself (setting up the 55 gal)...