The problems is people dont like being bored. Long, uneventfull, flights arent something that will attract alot of folks.
In the Aces High Event "Big Week" bomber pilots flew to 27k and we waited on them at 30k. They were 2 hour frames that were for the most part boring for 1 hour and 45 min.
Then you also need to look engine modeling. Bombers flew at a cruise and in formation in rl. In Aces High, and especially in Big Week, bombers fly at full throttle and and rarely in any recognizable formation that allows for their best defense. You see them fly in a large mass but not in anything resembling a "formation".
Then there's the "other" aspects such as:
"lets run the other side out of fuel since we know they have to be in the air to get to 30k and we only have 2 hours frames and they only have 1 hour of fuel, so we will wait till 30 min until end of hostilities before we hit the target. We will just stay out of radar until then".
As fighter pilots we also saw bombers pulling stuff like splitt esses, barrel rolls and immelmanns. All that adds up and folks see that for the most part its a waste of time, boring and unfun.
For the bomber pilots most events dont have "good targets" for bombers. In the Aces High Event "Battle of Britain" we were given the impossible task of bombing individual structures with the new bomb site. Bombers are boring as is. We had many many walkons and very few who could bomb. This forced us to lower altitudes where we had a better chance of putting our bombs on target. Had we been able to area bomb and the results been figured based on the amount of tonnage dropped on the paticular fields we could have followed more historic bombing practices.
In Big Week the "targets" where laid out to allow for area bombing but the we still used the laser bomb site. Even then you had guys fly all the way deep into "germany" at 50ft as if all of Europe was unpopulated. They did this to exploit the fact that the big week map had no small aaa.
So if you want an event that is fought at historical altitudes its important to eliminate boredom (air starts maybe?), we need targets that are designed with higher alt bombing in mind. You also need the bomber pilots to fly in decent formations so that they can be covered better by their escorts and that are arranged so their guns can be used to defend each other. I am sure its no fun for a bomber guy to spend 45 min grabbing just to be slapped out the sky.
Some fyi
In rl typical Bombing altitudes varied from as low as 19k to about 27k. Mostly between 22 and 25. The luftwaffe had long range radar that could pick up activity over East Anglia. They had numerous tactics and systems in place so there were very few instances where the luftwaffe were unaware of where the bombers were. The luftwaffe attempted to attack sections of the bomber stream that was less protected. Bomber streams were stretched out over 100s of miles. Even "Window" was defeated by tactics. (BTW the germans had the samething called "Duepple", just like window they were strips of silver paper). On top of that you had ground observers etc.
http://www.stable.demon.co.uk/general/bomb.htmAs the bombing campaign progressed the luftwaffe had fewer and fewer planes to attack better and better escorted bomber streams. Finally the allies could put so many fighters up where by they were able to hunt down and disrupt the gefechtsverband.
Also in an event like this some consideration has to made in the rules for kill/death. In real life the greatest effect the bombing campaign had was the overwhelming defeat of the luftwaffe in the west.
http://www.anesi.com/ussbs02.htmIf you force each side to be weary of their losses then there will be instances where the bombers get through with out being pecked to death by the attckers. If they attckers are aware that they need too live as much as they need to stop the bombers then you get a more "real" style of play. Same with the bombers, they may decide its more important to turn back, hit an alternate target or what ever.
So if you want more "realism" in the form of altitude then you need to include more "realism" all the way around. But in the end you should keep in mind that regardless of how real it is it needs to be fun. No one is in the AH military and no one has to "do what they are told". If they dont like it they dont show up. If they dont like your orders they go off on their own.