Hi again,
I was assuming that you will cross with a normal load (roughly up to 40 kgs). In general, there are porters who carry stuff across and I did that once without any problem before the new immigration office opened on the 2nd floor. Carrying your stuff up is not pleasant. I can tell as I often have my 20-30 kgs with me.
Assuming you can use the porter service, you wont have any issue until the drop-off at the Cambodian side. They do have those Indian tin cans in Poipet. That should do it. I also distinctly recall that some small groups used those. If you're lucky a classic Cambodian tuktuk will be waiting.

You wont be the first to carry a big load of stuff across into Cambodia. So all is arranged and easy, just the pricing depends on your patience and determination.

As you seem to come without own transport: The best you can do is to take the train from BKK and arrive well before 12 noon at the border. The train stops right next to the entrance to Thai immigration now. The porters will be waiting. Then cross and try to get a van at 1 pm to PP.

The other option is to get off the train at Aran. Sleep in Aran and get a tuktuk at 5.30 to the border. Have your breakfast first in Aran. You will be able to get the capitol bus to Orussey at 8.30 or 9 am and there are also others. So far I found the capitol bus the best for my needs. Nothing fancy but it never broke down. Take a seat in the middle of the bus for the benefit of your limbs in case something goes wrong.

Sleeping in Poipet is no fun and the food is sketchy compared to Aran.

Maybe you might consider Pailin as an alternative. The crossing is much smaller and the pickup for shared taxis is rather close to the checkpoint.

I passed through Poipet immigration this week. The destroyed hotel has been removed. No more detours and one can walk directly to the roundabout. It is actually a major improvement having having that casino out of the way.

I learnt my lessons and now whenever I cross from Thailand to poipet, I book for a night at the pheng chenda hotel. Far enough away from the danger zone, I got spat at by a passing motorbike with two guys onboard at night, but close enough to organise a minibus or shared taxi to Siem reap the next morning, when everything is sane. There's also an awesome pizza restaurant about 200metres away. For me it's now an enjoyable part of my border crossing experience. 80 baht or 3 dollars (both are accepted), will make you're tuktuk ride with all the guys harassing you once crossing a pleasant and easy experience. Demand a tuk tuk, not a motorbike. Stress free is the best way.