I hate that rule for blast templates, but its true you have to pull from the closes models to the firing model.
If I didn't hate the Dark Angels so much I'd get an Azrael for my guard blob. Wouldn't a Skyshield perform a similar function? They could still have the firepower and be armed for combat in case enemies get close to the back field.
I fought the guard blob with Azrael that was under a skyshield with a Shadowsword sitting on. Won the game effortless (lost a single Stormtalon and 3 scouts) because I just ignored it all game. He basically towered up in the corner and couldn't do anything.
Tough slow threats can be extremely easy to just ignore.