"carry throughs" as they are known tend to cost you more in lost time than you may realise. However, a job is a job in the early days when pennies count. Later, when you get get more established try to avoid them but you can't always.
I lost a couple of customers because I wouldn't do a third because there was no access. She wanted me to go over the garage roof and I wouldn't. The three houses were all friends and would pay for each other etc , so they wanted to all have the same cleaner.
Often when you get a referral you are more or less honour bound to take them on even if they are a carry through that you would normally turn down. I have one that is the mother of a good customer, access to the back is via an ally that starts about four houses along and then runs along the back of the gardens.
No way I could get my hoses down there.
A backpack and a compact brush is the easiest thing. Get some slip on overshoes for your feet from Toolstation.
I disagree about doing them trad. Carrying a big ladder through a house is a nightmare.