I'm a very small time beaver trapper, I caught 7 last year and that was my best year. I've always targeted the front foot, just because it seems easier. But I've been reading Hal Sullivan's Beaver 2000 and decided I'd like to try and catch one by the back door, just to say I can. But what I'm not sure of is how you get the beaver lined up. When I target a front foot and put a trap in front of a castor mound, no matter which way the beaver comes from his front feet end up in the right spot. But what prevents a beaver from coming from the left or the right and missing the trap when targeting the back foot? Guiding? An indentation in the bank? Do they always just come head on? I drew a picture to help explain.

Use of guide sticks will help

Cut a trench into the bank leading to your mound.

Give em a runway.

Put the trap out little farther out to target the back foot. Use guide sticks too. I used #3 or 4 jump traps growing up on beaver. I finally bought #5 makes a world of difference. I love snaring beavers.

Beaver will go all over the place,often at a castor mound they will go around your fencing and check out the castor from behind your trap.When they do that 90% of the time they hit the trap,foothold or 330 on the way out.I have watched many beaver work castor sets and get caught.
When you make your set find a natural place-brushy,or a natural indentation in the bank etc and use those spots to make your sets.For front foot catch you want the beaver walking just before he gets to the trap.I use a berm of sod,etc to do that.Still wont guarantee a front foot but helps.Oh yea,and bed your trap flush with the bottom.When you dig out the bed you can use that for the berm.
Often two guide sticks is all thats necessary to line up the beaver on the planned approach if you pick a good natural location for your sets.
The use of some small peeled sticks for eye appeal,and the placement of your castor scent will help to get the beaver to do what you want him to do.

Do y'all offset to one side or the other? I've been placing my #5s to one side of my sets.

Great advice!!!

A beaver goes on high alert when he approaches castor from a strange beaver. I use 330s on my castor mound sets and will tell you that I catch most if not all of my catches on his way back in the water. Why? He is looking for a fight with the dirty dog who peed on his fire hydrant. He carefully approaches and ends up avoiding strange things such as my 330. Once he swims/walks around and tops the mound with his scent, and sees that the coast is clear, he calms down, beats his chest and takes the easiest way back to the water. Right through my 330.

How far away from the bank do you set the foothold for the back foot catch?

18” out x 18” down (fist to elbow)

Trap off set.

Guide with 2 sticks stuck in bank poking out instead of up & down
Or guide with one vertical outside at the trap kind of like he is going around a corner.
Latter is most effective in current where they most often approach from downstream. Especially if downstream matches up with downwind.
Using BOCO’s berm or an under water stick to bump his chest then the same 18X18 from that
Steeper bank or a step up type bank put the mound back up off the water 2+ ft. So he must push up off bottom to get his chubby butt out- if it is deeper water at the base this is the easiest trap placement to get right IMO

River use a castor or food lure on top of a stick a foot or 3 from shore. 12-20 inches deep and stick up and out 8-12 inches. Trap pan back 18” and always down current. Chubby sits down stand as to raise his head up high enough to put his nose up to it- bam. Got that from Dale Billingsly’s video and have great results with it. Very fast and works where others are trapping.

If you have a large area and the beaver keep going all over the place you can even do this do this. It does not bother them at all. Leave a gap like I left here and they will head right through it. Bed you trap like Boco said and you are in business. I put my trap out about 16 or 18'' at this spot because the water drops off right after that and they were used to walking when they got that close.

Do yourself a favor buy Charlie Dobbins beaver book. He explains back footers in different situations very well. It's all about the slope of the bank and the depth of the water at the location.

Notches/ indents help a bunch.

Natural or man made slides or guide sticks to line them up. Then when their front feet get on the bank, I want the trap bedded where the back feet will drop down to push up the bank. The depth and distance from the bank varies a lot depending on the angle of the bank. But when you get it right, the beaver is caught before it has a clue that anything is up.