I think it comes down to good communication and support and understanding for one another really - I think it can be quite a change in relationship dynamic to go from both working to one being the 'breadwinner' and one the SAHP, and it can be hard on both parties. There's lots of threads on here about how hard it can be to be a SAHM - the boredom, the isolation etc, but I assume you have considered all that? I guess one thing you may not have thought about is the impact on your DH of becoming the sole breadwinner - MN kind of tends to imply it's a privilege and an easy ride to get to work full-time with the support of a SAHP, which of course it is to a large extent, but it can also be quite a lot of pressure - knowing the family is fully dependent on your income can make it hard if you are sick or feeling stressed (don't want to take time off or ask for help for fear of being sacked), you can feel anxious/guilty about taking time off work for school things or even to leave work on time so as to get home for bedtime or whatever (because if colleagues/your boss know your partner is a SAHP the expectation is they do 100% of child related things and your soul basically belongs to work). Plus it can really exacerbate existing dynamics where fathers (it's usually fathers) feel a bit shut out of young children's lives because they aren't the primary carer/aren't there most of the time, and then when they are 'in charge' they feel less confident and tend to defer to mum (mum can sometimes tend to hover/not trust the father fully), and so a vicious circle starts up. I think things have changed loads in the last year and it's going to be a difficult transition for him going from being at home mainly to travelling lots, you and he probably need to give some thought to how he can avoid being an absent father and how you are going to get a break - I can def see it becoming a routine where he's away all week that he just wants to flob out and relax when he gets home, meanwhile you've been lonely and frazzled alone with kids all week and are desperate for a break and some family time - I think time needs to be carved out somehow for (a) family time (b) individual relaxation and 'hobby' time (should be equal for you both) and (c) couple time without the children...
Also, boring stuff, but have you sorted out who is going to do what housework? It's a personal thing, some think the SAHP should do absolutely everything, some think their 'job' is purely to look after the children and housework should be divided 50:50 or even the breadwinner should do more, but my own view is all other things equal that the SAHP should be able to do the majority of the 'heavy lifting' housework such as laundry etc but that doesn't mean the working parent gets to act like a slob and not lift a finger around the house, they should do their fair share in the evenings/weekends like load/empty dishwasher, stick on a load of laundry or hang it up, cook a meal, do some gardening or DIY tasks at weekends - and these things should not be viewed as 'helping out' the SAHP but just being an equal partner in the home they live in! But it's quite personal and needs a good discussion really. If you can afford some help like a cleaner, gardener, meal service maybe that can be a massive help and also mean that weekends can really be prioritized for fun/family/relaxation rather than having to be spent catching up with household chores which can lead to a lot of resentment on both sides (I can say from bitter experience!).
Also have you had a thorough conversation about money which I think is super-important where one partner is becoming a SAHP - I know you've discussed whether you can cope on one salary but I mean more things like how will money be pooled, how will you access 'family money' and savings (can be easy to slip into a dynamic where the money-earning partner controls everything and dishes out 'housekeeping' or pocket money to a SAHP - I prefer a joint account based system in this scenario). Also have you reviewed/set a 'family' budget - things like money for days out/activities with the kids, lunches and snacks while out and about? Perversely you can find that when one partner goes SAHP your child related expenses can increase, because the SAHP naturally wants to do lots of fun, stimulating activities with the kids and get out and about to meet up with friends etc to make sure they aren't stuck at home all day but the expense can add up and again if it isn't discussed/agreed it can lead to one or both parties feeling resentful or confused...