That is the best survival strategy plus to PRACTICE emergency maneuvers in a safe place (braking& swerving),so that you can respond quickly.You wont have time to mull things over.
On the subject of chain tensioners the only reason to have one in the first place is that there are two chains to contend with,if the rear sprocket is not mounted properly it should be corrected with a better mounting like the 'clamshell' type.That should obviate the necessity of needing one.If there are two chains to take care of let the engine chain to be the primary one,that's where potential trouble lurks,so clearly this chain needs to be adjusted first if there are horizontal dropouts permitting this.Any slack in the other chain is not of that much consequence and is of course irrelevant with a deraileur setup.
With vertical dropouts a chain tensioner cannot be avoided.But I cannot understand why the type that put a substantial 'kink' in the chain (sometimes 30 degrees or more) is being used.This works fine as long as the engine is driving the bike,but puts a lot of transverse force on the tensioner when starting up and a great deal more if the engine seizes.The result can be that the tensioner gets dislodged from it's moorings,ends up in the rear wheel.Result a(highspeed) crash.If you do the analysis of forces ,you can show easily that the force on the tensioner is roughly proportional to the chain tension times the kink angle,so if it is 30 degrees instead of 10.It will 300lbs instead of 100.Moral of the story keep the angle as small as possible and use a solidl&robust type if it cannot be dislpensed with alltogether/
