We have the P&T travel cot and love it but have never used the side opening to put DD in, we always lower her in from the top. It wouldn't be hard at all to use the side opening but you would need to get right down at ground level so not sure it would be any better than leaning into it IYKWIM.

They are quite small too which is great for traveling but if your DS is use to a double bed, he may feel a little claustrophobic.

We love our cot though and would highly recommend it, especially for those who travel a lot like we do, but I'm not sure it'll really meet your needs ITMS.