Maybe just say to the men you are pregnant.

You're going to have to carry a table with you because giving massages on a bed can be very uncomfortable, as you're bending all the time and it's a big workout and a bit of a "killer" for your back. i wouldn't reccomend giving massages on a bed specially while you're pregnant. At least in a table you can use the correct posture. regarding covering the tummy you can always use some short sexy & loose negligee.

You can always buy a massage table carry-case with wheels (they sell them on the internet for like 40 pounds. ww.bestmassage.co.uk/couch-accessories.html ). Then carry it in the car with your boyfriend driving, have him help you get it out of the car and just roll it to the persons home (that's very easy and you won't need any female assistant). Keep in mind that rolling in with a big massage table in an hotel will raise questions from security/reception (talking from experience here) as portable tables are very recognizable. You can always tell them you're a massage therapist or a physio coming for a sports massage and your client is in room xyz. Just pray that you don't get one of those small hotels/ bed & breakfast with no elevator because then you'll need to get your boyfriend carry the table up the stairs a couple of floors. I'm not pregnant myself, exercise regularly in the gym and I'm pretty strong but have difficulties when carrying a table up the stairs.

Also keep in mind that folding, unfolding and putting in the carry case a table is something you will be able to do till your six month only. After that it will be very difficult in your state. Not trying to be discouraging in your new venue but keep in mind that pregnant professional massage therapists have to stop when they reach their 6th month (usually after their 5th month they work sitting in a stool). And all this assuming your pregnancy is going to go perfectly well with no complications or the doctor reccomending some bed rest which sometimes happen.

I'm not saying you shouldn't do it, but you need to keep in mind these things. I'm a massage therapist myself  talking from experience.

But if all this table thing sounds way too complicated just do bed massages and see how you feel about it (practice at home with the boyfriend before). But it can be quite a strain in the back after a while.