IMO< 4.5 is low enough, but a lot of things come into play with this, as first your actual experience with rifles ans scope, not everyone is FAST at getting a rifle settled in and using the scope to find a target!
something else to consider if being an ELK rifle
the larger the scope, objective is, the higher on the rifle it has to be mounted to fit, which can also lead to poor shooting form, can effect eye relief and how close or far away the scope has to be mounted to allow you to use!
also the HIGHER the magnification on the scope on AVERAGE< the poorer it is in low light,as an example, on average a 2x scope will allow seeing a lot longer in low light condition as in sun set, and have more light gathering abilities than say a 4.5x scope setting!
when you get up into 20+x powers, IMO, you start to get a LOT more mirage issue's too!
Most of my rifles so finding a target in one for me is almost a natural thing at this point! n ewer rifle hunters will NOT do as well, just due to lack of time behind a scope and experience that comes from time and doing so! however are set up with 4.5x14 in either 40 or 50 mm scopes,. I find them about perfect for most all condition I encounter, but I also have decades of experience using scopes!