In the UK we have certain
instrument departure routes which are for all jets/turbo-props >5700kg (thus subject to noise restrictions) leaving class D controlled airspace. These routes can be flown under VFR with the clearance containing a level band rather than a fixed level i.e. "Not above altitude 3000ft".
Here is an example:
http://www.ead.eurocontrol.int/pamsl..._2_EGGW_6-7_en
What you're proposing wouldn't really work in the UK because our airways and TMA's are class A (upto FL195). Otherwise, as long as the pilots can adhere to all the rules why not?