Uh.. way - you are talking bollocks i am afraid my friend.
I am aware you are a big lad genetically, but still - the numbers you are giving are too close to the world's elite.
You are only 6'2" (which while towering above me, isn't freakishly tall) and being just shy of 300lbs and 15% bodyfat.. You could be 250lbs and below 5% after water manipulation!
That said - i have no direct experience with those stats (300lbs, 15% on a 6'2" frame) so it may not look as impressive as it does in my head, and i am not 100% on the stats of the 250lb pro's on stage ATM without looking it up, but i am sure it is pretty close to you... thats comparing the pro's in the sport to you, not the other way around... hmm.
Are you confident you are 15%? This is very commonly miscalculated online, and it takes skill to measure bodyfat with callipers, while electronic devices are invariably wrong by a few percent (either way), with diet, time and drugs used affecting the reading - fine to measure progress, but no good to measure specific stats.
To give you an idea of what 15% looks like on a muscular physique (even if i do say so myself), look at my pics, i am around 14-15% there (although this is commonly said to be what 12% looks like, which looks very lean on a muscular physique).
I am well aware however of the 'BB Genetic Gamble', and apart from the fact my hand in that particular game is just a pair of two's, i know that when it all boils down to the best of the best, genetics are all that matters..
I have a friend - NEVER used AAS in his life - guess why; he puts on muscle so easily he never felt the need! (currently trying to get him to compete!!).
He is around 5'5" and i would say at least 220lbs. He is strong as fuck too and pisses all over me in size and strength - even though i use PED to help me (my Pair of Two's vs. his Ace Flush is miserable..).
To answer your question, if i had to choose, then yes - more drugs the lower you go - that is when calories and expenditure is highest and you are at most risk of catabolism.
As long as you allow lots of time off after (6+ months), i would suggest a 16-20wks of shorter cycles linked together (ie. a 16-20wk cycle using varying drugs and for varying purposes).
You could also do a blast and cruise type of deal throughout the 20 weeks and come off after - and i would merge the two to stay on for 20weeks with 1 week 'deloads' allowing partial recovery and allowing the body continued response to the supraphysiological androgen levels.
There is also the option of two 6-8 week cycles with a 6 or so weeks in-between - make sure to finish on short esters of course.
As for long term reducing the time off and still maintaining healthy endocrine function. Not in my opinion i am afraid.
Generally speaking i have found that over an extended time, those who use steroids regularly tend to require HRT earlier than those who do not - of course i have not done a study large enough to back this up, but it is a solid theory.
This is not to say all will need HRT by 40, or anything like that - but generally, the more you use the more you compromise your HPTA. it is what i believe and what i work by.
It is from a definite trend of recovery EITHER becoming harder little by little OR eventually 'catching up' to the user where they fail to recover fully ever again (not 20yr olds for the most part).
IMO even a regime of 2 moderate length cycles a year (8-10wk), well below the 26 week total needed to account for half the year spent 'on', over time leads to a compromised HPTA.
I cannot prove this as it is impossible to know who would have needed TRT naturally at that time or not - it is JIME.
So, all that in mind - if your number one priority is HPTA function i would avoid AAS(!), if your number one priority is BB then spend more time on than off, and for a little of both i agree with BR; shorter cycles, short esters are better - although my personal experience tells me that when this is done frequently, it still causes issues.. so i would say for the best mix of both somwhere along the lines of one to two 6 week cycles a year, or the equivalent of 1/4 of the year 'on', or 13 weeks.
These numbers (i say again) are my own - so i can't link you to an abstract of an article suggesting that 13 weeks a year of suppression is fine, but i can tell you that less inhibition will cause less problems than more..