If your available training time is going to drop and with the goals you have in mind for Sep and Oct I would suggest doing our gym based ME program (about 1 hour time commitment) in August up until 10 days before your Sep 4th run. No ME during that last 10 days to use as a taper period. Since you’ve been making aerobic base progress it would help to add 1 other intensity session each week. This could be an uphill interval session like 4×4 min w/ 3 min walking recovery done as hard as you can go for 4 minutes while not blowing up. You need to finish the last 4 min rep as strong as you did the first one. So, these are not sprints but paced efforts. This whole workout will take less than 45 min. If you can get on 1 longer Z1 run sometime during the week what will help to maintain that base you’ve built up. Any other short Z1 (not Z2) runs during he week will be bonuses.
If work load reduces in Sept I’d shift back to 3 weeks of higher Z1-2 volume and add back in the gym ME sessions 1x/wk.
I hope this helps.