I'd go with a tank AND a minigen or gen of your choice.
Unless you have temps under control throughout every season then a gen is gonna heat things up.
I got rid of my tank and regulator because I got a minigen, Now I'm kicking myself in the ass and looking for a decent deal on a tank and a regulator again.
This is to run in conjunction with the minigen. With the tank there too the gen won't run as much so I won't be fighting heat.
Even with a water cooled gen it will warm things up a bit.